A136684 Numbers k such that A120296(k) is prime.

3, 5, 8, 11, 20, 38, 61, 65, 71, 80, 83, 93, 233, 704, 1649, 2909, 3417, 3634, 9371

Offset: 1

Author

Alexander Adamchuk, Jan 16 2008

Keywords

• nonn
• more

Comments

A120296(k) = Numerator of Sum_{j=1..k} (-1)^(j+1)/j^4.

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, A136685, A136686.

Programs

Mathematica

Do[ f=Numerator[ Sum[ (-1)^(k+1)*1/k^4, {k,1,n} ] ]; If[ PrimeQ[f], Print[ {n,f} ] ], {n,1,100} ]
Select[Range[1000],PrimeQ[Numerator[Sum[(-1)^(k+1) 1/k^4,{k,#}]]]&] (* Harvey P. Dale, Aug 28 2012 *)

Extensions

More terms from Harvey P. Dale, Aug 28 2012

a(15)-a(19) from Robert Price, Apr 23 2019