A264879 Number of (2+1)X(n+1) arrays of permutations of 0..n*3+2 with each element having directed index change 0,1 0,-1 -2,0 or 1,1.

1, 0, 1, 1, 7, 20, 49, 175, 323, 1085, 2290, 6489, 15751, 41749, 105514, 276079, 706396, 1825615, 4714184, 12103729, 31297188, 80431077, 207561706, 534335127, 1377615603, 3548250067, 9145959294, 23561913471, 60719538527, 156456169973

Offset: 1

Author

R. H. Hardin, Nov 27 2015

Keywords

• nonn

Comments

Row 2 of A264878.

Examples

			All solutions for n=4
.10..2.12..4.14
..6..0..1..9..3
.11..5.13..7..8
		

Links

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

Crossrefs

Cf. A264878.

Formula

Empirical: a(n) = 10*a(n-2) +6*a(n-3) -42*a(n-4) -40*a(n-5) +117*a(n-6) +143*a(n-7) -222*a(n-8) -266*a(n-9) +272*a(n-10) +266*a(n-11) -222*a(n-12) -143*a(n-13) +117*a(n-14) +40*a(n-15) -42*a(n-16) -6*a(n-17) +10*a(n-18) -a(n-20)