A303526 Number of 3Xn 0..1 arrays with every element equal to 0, 1, 3, 4, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
4, 6, 18, 37, 80, 286, 916, 2532, 7477, 24285, 76820, 235117, 731307, 2316410, 7294592, 22810317, 71569571, 225378484, 708826544, 2225946457, 6995090976, 21998860077, 69164809009, 217385283885, 683342646350, 2148402980261
Offset: 1
Keywords
Examples
Some solutions for n=5 ..0..0..0..1..0. .0..1..0..0..0. .0..0..1..0..1. .0..1..1..0..1 ..0..1..1..1..0. .0..1..1..1..0. .1..1..1..0..1. .1..0..1..0..1 ..0..1..0..1..0. .0..0..0..1..0. .1..0..0..0..1. .1..0..1..0..1
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Crossrefs
Cf. A303525.
Formula
Empirical: a(n) = 2*a(n-1) +3*a(n-2) +a(n-3) +30*a(n-4) -53*a(n-5) -102*a(n-6) +11*a(n-7) -227*a(n-8) +351*a(n-9) +784*a(n-10) -242*a(n-11) +351*a(n-12) -361*a(n-13) -1069*a(n-14) +577*a(n-15) +8*a(n-16) +28*a(n-17) +22*a(n-18) -11*a(n-19) -a(n-20) for n>21
Comments