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A136685 Numbers n such that A136676(n) is prime. 8
2, 19, 51, 78, 84, 130, 294, 910, 2223, 2642, 3261, 4312, 4973, 7846, 9439 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

more,nonn

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

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Last modified May 31 00:29 EDT 2020. Contains 334747 sequences. (Running on oeis4.)