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 A264380 Number of (2+1) X (n+1) arrays of permutations of 0..n*3+2 with each element having directed index change 2,-2 -1,0 -1,2 1,0 or 0,-1. 1
 0, 1, 6, 9, 61, 121, 544, 1357, 5100, 14340, 49324, 147230, 485141, 1491460, 4812843, 15012153, 47950974, 150636184, 478755674, 1509249756, 4785018013, 15110309428, 47849311565, 151226992088, 478604645313, 1513243349293, 4787751445331 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 2*a(n-1) + 5*a(n-2) - 6*a(n-3) + 7*a(n-4) - 4*a(n-5) - a(n-6) + 5*a(n-7) - 4*a(n-8) + 2*a(n-9) - a(n-10). Empirical g.f.: x^2*(1 + 4*x - 8*x^2 + 19*x^3 - 17*x^4 + 13*x^5 - 8*x^6 + 2*x^7 - x^8) / (1 - 2*x - 5*x^2 + 6*x^3 - 7*x^4 + 4*x^5 + x^6 - 5*x^7 + 4*x^8 - 2*x^9 + x^10). - Colin Barker, Jan 07 2019 EXAMPLE Some solutions for n=4: ..1..6..5..4..7....1..2..3..8..7....5..6..3..8..7....5..2..3..8..7 ..0.11.10..3.14....0.11.10.13.12....0..1.10.11..4....0..1.10.13.12 ..2.12.13..8..9....5..6..4.14..9....2.12.13.14..9...11..6..4.14..9 CROSSREFS Row 2 of A264379. Sequence in context: A056425 A056416 A061401 * A284636 A046498 A119738 Adjacent sequences:  A264377 A264378 A264379 * A264381 A264382 A264383 KEYWORD nonn AUTHOR R. H. Hardin, Nov 12 2015 STATUS approved

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Last modified October 19 15:50 EDT 2019. Contains 328223 sequences. (Running on oeis4.)