A258471 Number of partitions of 2n into two sorts of parts having exactly n parts of the second sort.

1, 3, 11, 41, 155, 590, 2258, 8677, 33454, 129335, 501180, 1945997, 7569223, 29487091, 115029830, 449288570, 1756808604, 6876430799, 26940317004, 105635470645, 414528962220, 1627841401281, 6396735649200, 25152046015693, 98955167336425, 389526824102747

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..300

Formula

a(n) = A256193(2n,n).

a(n) ~ c * 4^n / sqrt(Pi*n), where c = 1 / A048651 = 1 / Product_{k>=1} (1-1/2^k) = 3.462746619455... . - Vaclav Kotesovec, May 31 2015

Crossrefs

Cf. A256193.

Sequence in context: A113437 A076540 A196472 * A176085 A356618 A129637

Adjacent sequences: A258468 A258469 A258470 * A258472 A258473 A258474

Keyword

nonn

Author

Alois P. Heinz, May 31 2015

Status

approved