A264246 Number of (2+1) X (n+1) arrays of permutations of 0..n*3+2 with each element having directed index change 0,0 1,1 0,-1 -1,1 or 0,-2.

3, 21, 95, 557, 3303, 18725, 105839, 602365, 3432551, 19548549, 111260799, 633294925, 3605196759, 20523670997, 116833710703, 665088330013, 3786103422919, 21552938831269, 122693118848735, 698447387572077

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 8*a(n-2) + 24*a(n-3) + 88*a(n-4) + 88*a(n-5) + 24*a(n-6) - 552*a(n-7) - 352*a(n-8) - 96*a(n-9) for n>10.

Empirical g.f.: x*(3 + 12*x + 8*x^2 + 32*x^3 + 104*x^4 - 32*x^5 - 408*x^6 - 448*x^7 + 32*x^8 + 128*x^9) / (1 - 3*x - 8*x^2 - 24*x^3 - 88*x^4 - 88*x^5 - 24*x^6 + 552*x^7 + 352*x^8 + 96*x^9). - Colin Barker, Jan 06 2019

Example

Some solutions for n=4:
..0..1..2..3..4....1..2..4..7..8....0..2..4..7..8....1..2..3..4..8
..5..7.11..8..9....5..0.11..9..3....6.10..1..9..3....6..0.11.12..9
.10.12..6.13.14...10.12..6.13.14...11..5.12.13.14...10..5.13..7.14

Crossrefs

Row 2 of A264244.

Sequence in context: A108970 A069017 A367997 * A144883 A362567 A074597

Adjacent sequences: A264243 A264244 A264245 * A264247 A264248 A264249

Keyword

nonn

Author

R. H. Hardin, Nov 09 2015

Status

approved