A101628 Denominator of partial sums of a certain series.

1, 35, 210, 30030, 12012, 1293292, 6466460, 743642900, 6692786100, 6016814703900, 12033629407800, 63606326869800, 63606326869800, 784965679900201800, 784965679900201800, 258253708687166392200, 19865669899012799400, 31905469837808435400, 31905469837808435400, 114827785946272559004600

Offset: 1

Author

Wolfdieter Lang, Dec 23 2004

Keywords

• nonn
• frac
• easy

Comments

The numerators are given in A101627.

Crossrefs

Cf. A101627 (numerators).

Programs

Mathematica

Denominator[Accumulate[Table[8/(9k^3-k),{k,20}]]] (* Harvey P. Dale, Jul 17 2014 *)

PARI

a(n) = denominator(24*sum(k=1, n, 1/((3*k-1)*(3*k)*(3*k+1)))); \\ Michel Marcus, Mar 01 2022

Formula

a(n)=denominator(s(n)) with s(n)=8*sum(1/((3*k-1)*k*(3*k+1)), k=1..n).

Extensions

More terms from Michel Marcus, Mar 01 2022