A292228 - OEIS

A292228

Denominators of partial sums of the series 1 + 2*Sum_{k >= 1} 1/(4*k^4 + 1).

1, 5, 65, 325, 13325, 812825, 13818025, 1561436825, 45281667925, 8195981894425, 482116582025, 434387040404525, 135963143646616325, 9925309486202991725, 4178555293691459516225, 154606545866584002100325, 16852113499457656228935425, 10330345575167543268337415525, 1415257343797953427762225926925, 1077010838630242558527053930389925

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OFFSET

0,2

COMMENTS

The corresponding numerators are given in A292227.

For the value of the series see A292227, and the Koecher reference given there.

LINKS

Robert Israel, Table of n, a(n) for n = 0..340

FORMULA

a(n) = denominator(s(n)) with the rationals (in lowest terms) s(n) = 1 + 2*Sum_{k=1..n} 1/(4*k^4 + 1), n >= 0.

EXAMPLE

See A292227.