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 A266471 Number of 4 X n binary arrays with rows and columns lexicographically nondecreasing and column sums nonincreasing. 1
 5, 12, 29, 66, 137, 261, 463, 775, 1237, 1898, 2817, 4064, 5721, 7883, 10659, 14173, 18565, 23992, 30629, 38670, 48329, 59841, 73463, 89475, 108181, 129910, 155017, 183884, 216921, 254567, 297291, 345593, 400005, 461092, 529453, 605722, 690569 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = (1/120)*n^5 + (1/24)*n^4 + (17/24)*n^3 - (25/24)*n^2 + (257/60)*n + 1. Conjectures from Colin Barker, Jan 10 2019: (Start) G.f.: x*(5 - 18*x + 32*x^2 - 28*x^3 + 11*x^4 - x^5) / (1 - x)^6. a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6. (End) EXAMPLE Some solutions for n=4: ..0..0..0..0....0..0..0..0....0..1..1..1....0..0..0..0....0..0..1..1 ..0..0..0..0....0..0..0..0....1..0..0..0....0..0..1..1....0..1..0..0 ..1..1..1..1....0..0..0..0....1..0..1..1....1..1..0..0....1..0..0..0 ..1..1..1..1....1..1..1..1....1..1..0..0....1..1..1..1....1..1..1..1 CROSSREFS Row 4 of A266470. Sequence in context: A196410 A000465 A283506 * A069306 A277088 A009412 Adjacent sequences:  A266468 A266469 A266470 * A266472 A266473 A266474 KEYWORD nonn,changed AUTHOR R. H. Hardin, Dec 29 2015 STATUS approved

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Last modified January 21 02:59 EST 2019. Contains 319344 sequences. (Running on oeis4.)