login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

Denominators of 6*(sum(1/binomial(2*k,k),k=1..n)-1/3), n>=1.
2

%I #5 Nov 10 2019 01:36:32

%S 1,1,10,70,105,2310,5460,20020,340340,6466460,461890,37182145,

%T 106234700,25160850,55454513400,1719089915400,573029971800,

%U 4011209802600,148414762696200,148414762696200,196290492598200,261655226633400600,392482839950100900,18446693477654742300,64563427171791598050

%N Denominators of 6*(sum(1/binomial(2*k,k),k=1..n)-1/3), n>=1.

%C Numerators are given by A130547.

%C For the rationals r(n):= 6*(sum(1/binomial(2*k,k),k=1..n)-1/3), n>=1, the Comtet reference and a W. Lang link see A130547.

%F a(n) = denominator(r(n)), n>=1.

%o (PARI) a(n) = denominator(6*(sum(k=1, n, 1/binomial(2*k,k)) - 1/3)); \\ _Michel Marcus_, Nov 09 2019

%Y Cf. A130547. (numerators).

%K nonn,frac,easy

%O 1,3

%A _Wolfdieter Lang_, Jul 13 2007

%E More terms from _Michel Marcus_, Nov 09 2019