A268770 Number of n X 4 0..2 arrays with some element plus some horizontally, vertically, diagonally or antidiagonally adjacent neighbor totalling two exactly once.

36, 100, 446, 2296, 10340, 46312, 198114, 837848, 3472210, 14245712, 57796288, 232692368, 930069146, 3696103032, 14612457534, 57516087912, 225502135332, 881077245816, 3431904293122, 13330760323672, 51652205043266

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) + 10*a(n-2) - 32*a(n-3) - 47*a(n-4) + 40*a(n-5) + 38*a(n-6) - 12*a(n-7) - 9*a(n-8) for n>10.

Empirical g.f.: 2*x*(18 - 22*x - 157*x^2 + 332*x^3 + 794*x^4 - 238*x^5 - 734*x^6 - 72*x^7 + 189*x^8 + 54*x^9) / (1 - 2*x - 7*x^2 + 2*x^3 + 3*x^4)^2. - Colin Barker, Jan 15 2019

Example

Some solutions for n=4:
..0..0..0..0. .0..0..0..0. .0..0..0..0. .2..1..2..2. .1..1..0..0
..1..0..0..1. .0..1..0..0. .0..0..1..0. .2..2..2..2. .0..0..0..0
..1..0..0..0. .0..0..0..1. .1..0..0..0. .2..2..2..2. .0..0..0..0
..0..0..0..0. .0..0..0..1. .0..1..0..0. .1..1..2..1. .0..0..0..0

Crossrefs

Column 4 of A268774.

Sequence in context: A085986 A027603 A250813 * A323064 A163246 A014738

Adjacent sequences: A268767 A268768 A268769 * A268771 A268772 A268773

Keyword

nonn

Author

R. H. Hardin, Feb 13 2016

Status

approved