A055609 Number of 3 X n binary matrices with no zero rows or columns, up to row and column permutation.

1, 5, 17, 42, 91, 180, 328, 565, 930, 1470, 2248, 3344, 4849, 6881, 9579, 13104, 17649, 23442, 30736, 39833, 51074, 64842, 81574, 101766, 125959, 154771, 188883, 229044, 276085, 330926, 394558, 468083, 552696, 649692, 760482, 886602, 1029691, 1191539, 1374065, 1579326

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (3, -1, -3, -1, 3, 6, -6, -3, 1, 3, 1, -3, 1).

Formula

G.f.: x*(x^8-x^7-x^6-2*x^5+2*x^4+x^3-3*x^2-2*x-1)/((x^3-1)^2*(x^2-1)^2*(x-1)^3).

Prog

(PARI) Vec((G(3, x) - G(2, x))*(1 - x) + O(x^30)) \\ G defined in A028657. - Andrew Howroyd, Feb 28 2023

Crossrefs

Column k=3 of A056152.

Cf. A024206, A002623, A002727.

Sequence in context: A239195 A111746 A088645 * A231703 A265193 A146720

Adjacent sequences: A055606 A055607 A055608 * A055610 A055611 A055612

Keyword

easy,nonn

Author

Vladeta Jovovic, Jun 03 2000

Extensions

Terms a(37) and beyond from Andrew Howroyd, Mar 25 2020

Status

approved