login
Denominator of partial sums of a certain series.
1

%I #11 Mar 01 2022 07:25:51

%S 1,35,210,30030,12012,1293292,6466460,743642900,6692786100,

%T 6016814703900,12033629407800,63606326869800,63606326869800,

%U 784965679900201800,784965679900201800,258253708687166392200,19865669899012799400,31905469837808435400,31905469837808435400,114827785946272559004600

%N Denominator of partial sums of a certain series.

%C The numerators are given in A101627.

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

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

%o (PARI) a(n) = denominator(24*sum(k=1, n, 1/((3*k-1)*(3*k)*(3*k+1)))); \\ _Michel Marcus_, Mar 01 2022

%Y Cf. A101627 (numerators).

%K nonn,frac,easy

%O 1,2

%A _Wolfdieter Lang_, Dec 23 2004

%E More terms from _Michel Marcus_, Mar 01 2022