A264585 Number of (2+1) X (n+1) arrays of permutations of 0..n*3+2 with each element having directed index change 1,0 0,-1 1,2 or -1,1.

1, 2, 4, 10, 16, 56, 128, 320, 784, 1792, 4480, 10496, 25600, 62080, 149504, 363520, 872448, 2109440, 5088256, 12279808, 29683712, 71622656, 173031424, 417669120, 1008336896, 2434695168, 5877530624, 14192476160, 34265432064, 82732646400

Offset

1,2

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 16*a(n-5) - 16*a(n-6) + 32*a(n-7) - 64*a(n-10).

Empirical g.f.: x*(1 + 2*x^3 - 4*x^4 + 8*x^5 - 16*x^8) / (1 - 2*x - 16*x^5 + 16*x^6 - 32*x^7 + 64*x^10). - Colin Barker, Jan 08 2019

Example

Some solutions for n=4:
..1..2..3..7..8....1..5..3..4..8....1..5..3..7..8....1..5..6..4..8
..0.10.11.12..4....6.10..0..9..2....0.10..2.12..4....0.10..2..3.13
..5..6.13.14..9...11.12.13.14..7...11..6.13.14..9...11.12..7.14..9

Crossrefs

Row 2 of A264583.

Sequence in context: A348305 A277918 A238720 * A077635 A125754 A097870

Adjacent sequences: A264582 A264583 A264584 * A264586 A264587 A264588

Keyword

nonn

Author

R. H. Hardin, Nov 18 2015

Status

approved