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A264423 Number of (2+1) X (n+1) arrays of permutations of 0..n*3+2 with each element having directed index change 0,1 2,2 1,0 -1,2 -2,-1 or -1,-1. 1
1, 3, 12, 37, 119, 385, 1252, 4061, 13166, 42687, 138419, 448847, 1455443, 4719435, 15303308, 49622768, 160907641, 521761825, 1691873630, 5486097814, 17789312907, 57683924784, 187046863084, 606521298870, 1966716147754, 6377306803896 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 3*a(n-1) + a(n-3) + 5*a(n-4) + a(n-7).

Empirical g.f.: x*(1 + 3*x^2 + x^5) / ((1 + x^2 + x^3)*(1 - 3*x - x^2 + x^3 - x^4)). - Colin Barker, Jan 07 2019

EXAMPLE

Some solutions for n=4:

..6..7..1..2..3....6..0..1..9..3....6.12.13.14..7...11.12.13..2..3

..0.12.13.14..4...11.12..2.14..4....0..1..2..3..4....0..1..6.14..4

..5.10.11..8..9....5.10..7..8.13....5.10.11..8..9....5.10..7..8..9

CROSSREFS

Row 2 of A264422.

Sequence in context: A255610 A022727 A290930 * A240193 A319077 A008907

Adjacent sequences:  A264420 A264421 A264422 * A264424 A264425 A264426

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 12 2015

STATUS

approved

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Last modified October 21 04:00 EDT 2021. Contains 348141 sequences. (Running on oeis4.)