A059776 Three-quadrant Ferrers graphs that partition n.

1, 2, 5, 11, 24, 48, 95, 178, 328, 585, 1025, 1754, 2958, 4897, 8002, 12889, 20523, 32289, 50296, 77550, 118521, 179553, 269881, 402532, 596178, 876942, 1281777, 1862015, 2689405, 3862891, 5519403, 7846393, 11100970, 15632733, 21917280

Offset

0,2

References

G. E. Andrews, Three-quadrant Ferrers graphs, Indian J. Math., 42 (No. 1, 2000), 1-7.

Links

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000

Formula

a(n) ~ exp(Pi*sqrt(2*n)) / (2^(11/2) * n^(3/2)). - Vaclav Kotesovec, Jul 12 2018

Maple

t1 := add( (-1)^(j)*q^(j*(j+1)/2)*(1-q^(j+1))/(1-q), j=0..101); t3 := mul((1-q^n)^3, n=1..101); series(t1/t3, q, 101);

Mathematica

nmax = 50; CoefficientList[Series[Sum[(-1)^k*x^(k*(k+1)/2)*(1 - x^(k + 1))/(1 - x), {k, 0, nmax}]/Product[(1 - x^k)^3, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Jul 11 2018 *)

Crossrefs

Cf. A000041, A001522, A059777.

Sequence in context: A208952 A091358 A091359 * A091360 A300277 A294378

Adjacent sequences: A059773 A059774 A059775 * A059777 A059778 A059779

Keyword

nonn,easy

Author

N. J. A. Sloane, Feb 21 2001

Status

approved