A130040 Denominators of partial sums of a series for the inverse of the arithmetic-geometric mean (agM) of 2/sqrt(5) and 1.

1, 20, 1600, 6400, 409600, 204800000, 16384000000, 327680000000, 83886080000000, 67108864000000, 671088640000000000, 13421772800000000000, 4294967296000000000000, 17179869184000000000000

Offset

0,2

Comments

See the references and the W. Lang link under A130039.

Links

Table of n, a(n) for n=0..13.

Formula

a(n) = denom(sum((((2*j)!/(j!^2))^2) *((1/(5*2^4))^j),j=0..n)), n>=0.

Crossrefs

Sequence in context: A203481 A177608 A177610 * A331563 A250018 A177604

Adjacent sequences: A130037 A130038 A130039 * A130041 A130042 A130043

Keyword

nonn,frac,easy

Author

Wolfdieter Lang Jun 01 2007

Status

approved