A136685 Numbers k such that A136676(k) is prime.

2, 19, 51, 78, 84, 130, 294, 910, 2223, 2642, 3261, 4312, 4973, 7846, 9439

Offset

1,1

Comments

A136676(k) = Numerator of Sum_{j=1..k} (-1)^(j+1)/j^5.

Links

Table of n, a(n) for n=1..15.

Eric Weisstein's World of Mathematics, Harmonic Number

Mathematica

Do[ f=Numerator[ Sum[ (-1)^(k+1)*1/k^5, {k, 1, n} ] ]; If[ PrimeQ[f], Print[ {n, f} ] ], {n, 1, 130} ]

Crossrefs

Cf. A058313, A119682, A136675, A120296, A136676, A136677.

Cf. A001008, A007406, A007408, A007410, A099828, A103345.

Cf. A136681, A136682, A136683, A136684, A136686.

Sequence in context: A296251 A307554 A031911 * A226489 A125201 A215392

Adjacent sequences: A136682 A136683 A136684 * A136686 A136687 A136688

Keyword

nonn,more

Author

Alexander Adamchuk, Jan 16 2008

Extensions

a(7)-a(8) from Amiram Eldar, Mar 14 2019

a(9)-a(15) from Robert Price, Apr 16 2019

Status

approved