The On-Line Encyclopedia of Integer Sequences (OEIS)

Revisions by Amiram Eldar

(See also Amiram Eldar's wiki page
and changes approved by Amiram Eldar)

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A063449

Numbers k for which d(k+1) > 2*d(k), where d(j) = A000005(j).
(history; published version)

#24 by Amiram Eldar at Sat Mar 08 04:55:01 EST 2025

STATUS

editing

proposed

#23 by Amiram Eldar at Sat Mar 08 04:54:52 EST 2025

PROG

(PARI) { n=0; for is(m) =1, 10^9, if ( numdiv(m + 1) > 2*numdiv(m), write("b063449.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 21 2009

STATUS

proposed

editing

Discussion

Sat Mar 08

04:55

Amiram Eldar: Yes.

A065301

Numbers k such that both k and the sum of its divisors are squarefree numbers.
(history; published version)

#32 by Amiram Eldar at Sat Mar 08 04:54:19 EST 2025

STATUS

editing

proposed

#31 by Amiram Eldar at Sat Mar 08 04:54:12 EST 2025

PROG

(PARI) { n=0; for is(m ) = 1, 10^9, if (abs(moebius(m))==1 && abs(moebius(sigma(m)))==1, write("b065301.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Oct 15 2009

STATUS

proposed

editing

Discussion

Sat Mar 08

04:54

Amiram Eldar: Yes.

A063450

Numbers k such that d(k+1) < 2*d(k), where d() is the number of divisors function A000005.
(history; published version)

#21 by Amiram Eldar at Sat Mar 08 04:53:32 EST 2025

STATUS

editing

proposed

#20 by Amiram Eldar at Sat Mar 08 04:53:25 EST 2025

PROG

(PARI) { n=0; for is(m) =1, 10^9, if ( numdiv(m + 1) < 2*numdiv(m), write("b063450.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 21 2009

STATUS

proposed

editing

Discussion

Sat Mar 08

04:53

Amiram Eldar: Yes.

A063446

Integers m such that d(m+1) = 2*d(m), where d(m) = A000005(m).
(history; published version)

#34 by Amiram Eldar at Sat Mar 08 03:03:41 EST 2025

STATUS

editing

proposed

A063449

Numbers k for which d(k+1) > 2*d(k), where d(j) = A000005(j).
(history; published version)

#22 by Amiram Eldar at Sat Mar 08 03:03:40 EST 2025

STATUS

editing

proposed

Discussion

Sat Mar 08

04:43

Michel Marcus: pari: keep only is(m) = numdiv(m + 1) > 2*numdiv(m);   ??

A063450

Numbers k such that d(k+1) < 2*d(k), where d() is the number of divisors function A000005.
(history; published version)

#19 by Amiram Eldar at Sat Mar 08 03:03:39 EST 2025

STATUS

editing

proposed

Discussion

Sat Mar 08

04:46

Michel Marcus: pari: keep only is(m) = numdiv(m + 1) < 2*numdiv(m);   ?

A065301

Numbers k such that both k and the sum of its divisors are squarefree numbers.
(history; published version)

#30 by Amiram Eldar at Sat Mar 08 03:03:39 EST 2025

STATUS

editing

proposed

Discussion

Sat Mar 08

04:44

Michel Marcus: pari: keep only is(m) = abs(moebius(m))==1 && abs(moebius(sigma(m)))==1   ?