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

Author

Alexander Adamchuk, Jan 16 2008

Keywords

• nonn
• more

Comments

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

Links

• Eric Weisstein's World of Mathematics, Harmonic Number

Crossrefs

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

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

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

Programs

Mathematica

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

Extensions

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

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