A101630 Denominator of partial sums of a certain series.

1, 42, 6006, 204204, 3879876, 446185740, 38818159380, 2406725881560, 89048857617720, 3651003162326520, 156993135980040360, 51650741737433278440, 2737489312083963757320, 2737489312083963757320

Offset: 1

Author

Wolfdieter Lang, Dec 23 2004

Keywords

• nonn
• frac
• easy

Comments

The numerators are given in A101629.

a(13) and a(14) are indeed identical, namely 2737489312083963757320.

Formula

a(n)=denominator(s(n)) with s(n)=15*sum(1/((4*k-1)*k*(4*k+1)), k=1..n).