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A264622 Number of (n+1) X (1+1) arrays of permutations of 0..n*2+1 with each element having directed index change -2,0 -1,0 0,-1 or 1,1. 1
0, 1, 2, 1, 1, 4, 6, 5, 7, 15, 21, 23, 34, 58, 80, 101, 149, 230, 319, 431, 629, 928, 1299, 1810, 2617, 3784, 5336, 7536, 10828, 15521, 21992, 31236, 44713, 63862, 90741, 129177, 184524, 263178, 374521, 533619, 761403, 1085401, 1545839, 2203162 (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) = a(n-3) + 2*a(n-4) + a(n-5).

Empirical g.f.: x^2*(1 + x)^2 / (1 - x^3 - 2*x^4 - x^5). - Colin Barker, Jan 08 2019

EXAMPLE

All solutions for n=4:

..1..5

..3..0

..8..2

..7..4

..9..6

CROSSREFS

Column 1 of A264628.

Sequence in context: A273891 A034870 A324224 * A275017 A141036 A294947

Adjacent sequences:  A264619 A264620 A264621 * A264623 A264624 A264625

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 19 2015

STATUS

approved

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Last modified June 5 18:48 EDT 2020. Contains 334854 sequences. (Running on oeis4.)