OFFSET
0,2
COMMENTS
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1154
Eric Weisstein's World of Mathematics, Pi Formulas
FORMULA
a(n) = numerator(Sum_{k=0..n} (2^k)/A002457(k)).
EXAMPLE
b(0) = 1, so a(0) = 1.
b(1) = 4/3, so a(1) = 4.
b(2) = 22/15, so a(2) = 22.
b(3) = 32/21, so a(3) = 32.
b(4) = 488/315, so a(4) = 488.
PROG
(PARI) a(n) = numerator(sum(k=0, n, (2^k * (k!)^2)/(2*k + 1)!)); \\ Michel Marcus, Oct 22 2016
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Seiichi Manyama, Oct 22 2016
STATUS
approved