The On-Line Encyclopedia of Integer Sequences (OEIS)

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Showing entries 1-10 | older changes

A085747

Least positive k such that n! + k is a semiprime.
(history; published version)

#55 by OEIS Server at Sat Mar 08 09:54:52 EST 2025

LINKS

Tyler Busby, <a href="/A085747/b085747_3.txt">Table of n, a(n) for n = 1..107</a> (terms 1..99, 101..103, and 105 from Max Alekseyev, terms 100 and 104 from Sean A. Irvine)

A381419

a(1) = 1; for n > 1, a(n) is the smallest unused positive number that is coprime to a(n-1) and has a different binary weight than a(n-1).
(history; published version)

#13 by OEIS Server at Sat Mar 08 09:41:12 EST 2025

LINKS

Scott R. Shannon, <a href="/A381419/b381419_1.txt">Table of n, a(n) for n = 1..10000</a>

A381420

a(1) = 1, a(2) = 3; for n > 2, a(n) is the smallest unused positive number that shares a factor with a(n-1) and has a different binary weight than a(n-1).
(history; published version)

#9 by OEIS Server at Sat Mar 08 09:41:04 EST 2025

LINKS

Scott R. Shannon, <a href="/A381420/b381420_1.txt">Table of n, a(n) for n = 1..10000</a>

A381821

Fixed points of A381419.
(history; published version)

#8 by OEIS Server at Sat Mar 08 09:40:54 EST 2025

LINKS

Scott R. Shannon, <a href="/A381821/b381821_1.txt">Table of n, a(n) for n = 1..741</a>

A381359

E.g.f. A(x) satisfies 1 - A'(x)^2 + 4*A(x)^3 = 0.
(history; published version)

#27 by OEIS Server at Sat Mar 08 09:40:32 EST 2025

LINKS

Paul D. Hanna, <a href="/A381359/b381359_1.txt">Table of n, a(n) for n = 0..200</a>

A381368

a(n) is the least k > n for which prime(n) + prime(k) is a square.
(history; published version)

#13 by OEIS Server at Sat Mar 08 08:47:33 EST 2025

LINKS

Felix Huber, <a href="/A381368/b381368_1.txt">Table of n, a(n) for n = 1..10000</a>

A085322

Terms m of A003337 such that m+1 is also in A003337. I.e., smaller one of two consecutive numbers, both equal to a sum of three 4th powers.
(history; published version)

#19 by OEIS Server at Sat Mar 08 06:00:56 EST 2025

LINKS

Amiram Eldar, <a href="/A085322/b085322_1.txt">Table of n, a(n) for n = 1..89</a> (calculated from the b-file at A003337)

A077067

Squarefree numbers of the form prime + 1.
(history; published version)

#22 by OEIS Server at Sat Mar 08 06:00:51 EST 2025

LINKS

Amiram Eldar, <a href="/A077067/b077067_1.txt">Table of n, a(n) for n = 1..10000</a>

A065301

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

#35 by OEIS Server at Sat Mar 08 06:00:48 EST 2025

LINKS

Amiram Eldar, <a href="/A065301/b065301_1.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Harry J. Smith)

A063450

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

#24 by OEIS Server at Sat Mar 08 06:00:41 EST 2025

LINKS

Amiram Eldar, <a href="/A063450/b063450_1.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Harry J. Smith)