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Revision History for A001082

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Generalized octagonal numbers: k*(3*k-2), k=0, +- 1, +- 2, +-3, ...
(history; published version)
#203 by Charles R Greathouse IV at Sun Feb 16 08:32:22 EST 2025
LINKS

Eric Weisstein's World of Mathematics, <a href="httphttps://mathworld.wolfram.com/QuintupleProductIdentity.html">Quintuple Product Identity</a>.

Discussion
Sun Feb 16
08:32
OEIS Server: https://oeis.org/edit/global/3014
#202 by Peter Bala at Wed Dec 25 14:54:31 EST 2024
COMMENTS

Exponents of q in the expansion of Sum_{n >= 0} ( q^n * Product_{k = 1..n} (1 - q^(2*k-1)) ) = 1 + q - q^5 - q^8 + q^16 + q^21 - - + + .... - Peter Bala, Dec 03 2020

Exponents of q in the expansion of Product_{n >= 1} (1 - q^(6*n))*(1 + q^(6*n-1))*(1 + q^(6*n-5)) = 1 + q + q^5 + q^8 + q^16 + q^21 + .... - Peter Bala, Dec 09 2020

Exponents of q in the expansion of Product_{n >= 1} (1 - q^n)^2*(1 - q^(4*n))^2 /(1 - q^(2*n)) = 1 - 2*q + 4*q^5 - 5*q^8 + 7*q^16 - + ... (a consequence of the quintuple product identity). The series coefficients are a signed version of A001651. - Peter Bala, Feb 16 2021

Apart from the first two terms, the exponents of q in the expansion of Sum_{n >= 1} q^(3*n+2) * (Product_{k = 2..n} 1 - q^(2*k-1)) = q^5 + q^8 - q^16 - q^21 + + - - ... (in Andrews, equation 8, replace q with q^2 and set x = q).

Exponents of q^2 in the expansion in powers of q^2 of Sum_{n >= 0} q^n / (Product_{k = 1..n+1 } 1 + q^(2*k-1)) = 1 + (q^2)^1 - (q^2)^5 - (q^2)^8 + (q^2)^16 + (q^2)^21 - - + + ... (Chen, equation 22). (End)

Exponents in the expansion of Product_{n >= 1} (1 - q^(2*n-1))^2 * (1 - q^(4*n-2)) * (1 - q^(4*n))^3 = 1 - 2*q + 4*q^5 - 5*q^8 + 7*q^16 - 8*q^21 + 10*q^33 - 11*q^40 + - ... (the unsigned coefficients are the positive integers not divisible by 3). - Peter Bala, Dec 25 2024

STATUS

editing

approved

#201 by Peter Bala at Wed Dec 25 12:22:35 EST 2024
COMMENTS

Exponents of q in the expansion of Sum_{n >= 0} ( q^n * Product_{k = 1..n} (1 - q^(2*k-1)) ) = 1 + q - q^5 - q^8 + q^16 + q^21 - - + + .... - Peter Bala, Dec 03 2020

Exponents of q in the expansion of Product_{n >= 1} (1 - q^(6*n))*(1 + q^(6*n-1))*(1 + q^(6*n-5)) = 1 + q + q^5 + q^8 + q^16 + q^21 + .... - Peter Bala, Dec 09 2020

Exponents of q in the expansion of Product_{n >= 1} (1 - q^n)^2*(1 - q^(4*n))^2 /(1 - q^(2*n)) = 1 - 2*q + 4*q^5 - 5*q^8 + 7*q^16 - + ... (a consequence of the quintuple product identity). The series coefficients are a signed version of A001651. - Peter Bala, Feb 16 2021

Apart from the first two terms, the exponents of q in the expansion of Sum_{n >= 1} q^(3*n+2) * (Product_{k = 2..n} 1 - q^(2*k-1)) = q^5 + q^8 - q^16 - q^21 + + - - ... (in Andrews, equation 8, replace q with q^2 and set x = q).

Exponents of q^2 in the expansion in powers of q^2 of Sum_{n >= 0} q^n / (Product_{k = 1..n+1 } 1 + q^(2*k-1)) = 1 + (q^2)^1 - (q^2)^5 - (q^2)^8 + (q^2)^16 + (q^2)^21 - - + + ... (Chen, equation 22). (End)

Exponents in the expansion of Product_{n >= 1} (1 - q^(2*n-1))^2 * (1 - q^(4*n-2)) * (1 - q^(4*n))^3 = 1 - 2*q + 4*q^5 - 5*q^8 + 7*q^16 - 8*q^21 + 10*q^33 - 11*q^40 + - ... (the unsigned coefficients are the positive integers not divisible by 3). - Peter Bala, Dec 25 2024

STATUS

approved

editing

#200 by Michael De Vlieger at Mon Dec 16 13:28:40 EST 2024
STATUS

reviewed

approved

#199 by Amiram Eldar at Mon Dec 16 12:43:38 EST 2024
STATUS

proposed

reviewed

#198 by Patrick De Geest at Mon Dec 16 12:40:52 EST 2024
STATUS

editing

proposed

#197 by Patrick De Geest at Fri Dec 13 17:42:30 EST 2024
COMMENTS

Integer quotients of (x*(x+1)*(x+2))/(x+(x+1)+(x+2)) for positive values of x which are given by A032766. - Patrick De Geest, Dec 13 2024

STATUS

proposed

editing

#196 by Patrick De Geest at Fri Dec 13 16:55:56 EST 2024
STATUS

editing

proposed

Discussion
Fri Dec 13
17:24
Michel Marcus: x+(x+1)+(x+2) = 3x+3, so your quotient is (x*(x+1)*(x+2))/(3x+3) = (x*(x+2))/3 , so your comment is the same as the one by Bruno Berselli, Jul 18 2016 , no ??
17:35
Andrew Howroyd: re 14:38 Please note that is considered a conjecture. You should not enter unproven statements into oeis without saying so. If you do not have proof of a statement you must write something like: It appears that ....
17:42
Patrick De Geest: I see now that my comment corresponds to Berselli's. I will delete my entry.
#195 by Patrick De Geest at Fri Dec 13 16:55:40 EST 2024
COMMENTS

Integer solutions quotients of (x*(x+1)*(x+2))/(x+(x+1)+(x+2)). Values for positive values of x which are given by A032766. - Patrick De Geest, Dec 13 2024

STATUS

proposed

editing

#194 by Michel Marcus at Fri Dec 13 12:26:11 EST 2024
STATUS

editing

proposed

Discussion
Fri Dec 13
14:13
N. J. A. Sloane: What do you mean by "Integer solutions of (x*(x+1)*(x+2))/(x+(x+1)+(x+2))." ? Do mean "Zeros of"?  Or maybe you just forgot the rest of the equation ?
14:15
N. J. A. Sloane: And if you meant "Zeros of", why not omit the denominator?
14:38
Patrick De Geest: I ran --> for(x=1,50,print(x,"  ",x*(x+1)*(x+2)/(x+x+1+x+2)) ) in pari/gp
and saw that the integer solutions corresponded with the sequence.
14:47
Patrick De Geest: I mean 'integer quotients'.