A264015 Number of (n+1) X (6+1) arrays of permutations of 0..n*7+6 with each element having index change +-(.,.) 0,0 1,2 or 2,2.

32, 1869, 146410, 7320500, 398967250, 21860843125, 1201888840625, 66099082156250, 3635200164062500, 199922408907031250, 10994987257267578125, 604683325796494140625, 33255329542371191406250, 1828919197622934570312500

Offset

1,1

Links

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

Formula

Empirical: a(n) = 60*a(n-1) - 300*a(n-2) + 1500*a(n-3) - 7500*a(n-4) + 3125*a(n-5) for n>7.

Empirical g.f.: x*(32 - 51*x + 43870*x^2 - 951400*x^3 + 1096750*x^4 - 86739375*x^5 + 39912500*x^6) / ((1 - 5*x)*(1 - 55*x + 25*x^2 - 1375*x^3 + 625*x^4)). - Colin Barker, Jan 03 2019

Example

Some solutions for n=3:
..9..1.11.12.13..5..6....0..1..2..3.20..5..6....9.10.18.19..4..5..6
..7.24..0.19.27..3..4...16..8.25.19.11.12.13....7.24..0.26.27.12.13
.23.15.16.26..2.10.20...23.15..7.26.18.10..4...23.15.25..1..2..3.20
.21.22.14..8.25.17.18...21.22.14.24..9.17.27...21.22.14..8.16.17.11

Crossrefs

Column 6 of A264017.

Sequence in context: A299666 A300257 A248073 * A239646 A323540 A304123

Adjacent sequences: A264012 A264013 A264014 * A264016 A264017 A264018

Keyword

nonn

Author

R. H. Hardin, Nov 01 2015

Status

approved