A128493 Denominators of partial sums for a series for (Pi^4)/96.

1, 81, 50625, 121550625, 9845600625, 144149438750625, 4117052120156600625, 4117052120156600625, 343860310127599440800625, 44812219476138886724578250625, 44812219476138886724578250625

Offset: 1

Author

Wolfdieter Lang Apr 04 2007

Keywords

• nonn
• frac
• easy

Comments

Numerators are given in A120269.

See the comments and the W. Lang link under A120269.

Programs

Mathematica

a[n_] := (Pi^4 - PolyGamma[3, n + 1/2])/96 // Simplify // Denominator; Table[a[n], {n, 1, 11}] (* Jean-François Alcover, Dec 05 2013 *)

Formula

a(n)=denominator(r(n)) with r(n):=sum(1/(2*k-1)^4,k=1..n).