A264315 Number of (2+1)X(n+1) arrays of permutations of 0..n*3+2 with each element having directed index change 0,0 0,1 1,0 -1,-2 or 0,2.

1, 20, 139, 735, 4103, 24153, 137703, 781453, 4441735, 25301221, 144075295, 820164205, 4668417719, 26575597941, 151287649935, 861229928957, 4902653550311, 27908998988293, 158875877400831, 904423174974925

Offset

1,2

Comments

Row 2 of A264313.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) +10*a(n-2) +18*a(n-3) +72*a(n-4) +40*a(n-5) -152*a(n-6) -728*a(n-7) -400*a(n-8) +1008*a(n-9) +704*a(n-10) +192*a(n-11)

Example

Some solutions for n=4
..0..8..1..3..2....7..0..1..3..4....0..1..9..3..2....0..1..9..2..4
.12..6.14..7..4...12..5..2..8..9....5..6.14..8..4....5..6.14..3..8
..5.11.10.13..9...10..6.11.13.14...10.11..7.13.12...10.11..7.13.12

Crossrefs

Cf. A264313.

Sequence in context: A144965 A262140 A140301 * A264308 A328174 A236988

Adjacent sequences: A264312 A264313 A264314 * A264316 A264317 A264318

Keyword

nonn

Author

R. H. Hardin, Nov 11 2015

Status

approved