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 A055609 Number of 3 X n binary matrices with no zero rows or columns, up to row and column permutation. 9
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Andrew Howroyd, Table of n, a(n) for n = 1..1000 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

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Last modified April 23 02:53 EDT 2024. Contains 371906 sequences. (Running on oeis4.)