A136686 Numbers k such that A136677(k) is prime.

19, 47, 164, 235, 504, 1109, 1112, 5134, 9222

Offset

1,1

Comments

A136677(k) = Numerator of Sum_{j=1..k} (-1)^(j+1)/j^6.

Links

Table of n, a(n) for n=1..9.

Eric Weisstein's World of Mathematics, Harmonic Number.

Mathematica

Do[ f=Numerator[ Sum[ (-1)^(k+1)*1/k^6, {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, A136685.

Sequence in context: A289728 A141973 A165672 * A130413 A156376 A063306

Adjacent sequences: A136683 A136684 A136685 * A136687 A136688 A136689

Keyword

nonn,hard,more

Author

Alexander Adamchuk, Jan 16 2008

Extensions

a(4)-a(5) from Hiroaki Yamanouchi, Sep 22 2014

a(6) from Amiram Eldar, Mar 14 2019

a(7)-a(9) from Robert Price, Apr 20 2019

Status

approved