A281055 Number of nX7 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
13, 535, 2828, 10570, 32370, 87995, 221212, 526340, 1201939, 2661939, 5752796, 12190173, 25413086, 52258597, 106216045, 213723050, 426288170, 843735147, 1658596579, 3240610144, 6297012052, 12175728717, 23437264280, 44930659786
Offset: 1
Keywords
Examples
Some solutions for n=4 ..0..1..0..1..0..0..1. .0..1..1..1..0..1..0. .0..1..0..1..1..1..0 ..0..1..0..1..1..0..1. .0..1..0..1..0..1..0. .0..1..0..1..0..0..1 ..0..1..0..0..1..0..1. .0..1..0..1..0..1..0. .0..1..0..1..1..0..1 ..0..1..1..1..1..0..1. .1..0..1..0..1..1..0. .0..1..0..0..1..0..0
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Crossrefs
Cf. A281056.
Formula
Empirical: a(n) = 5*a(n-1) -6*a(n-2) -4*a(n-3) +5*a(n-4) +9*a(n-5) -3*a(n-6) -3*a(n-7) -3*a(n-8) -9*a(n-9) +6*a(n-11) +8*a(n-12) +2*a(n-13) +3*a(n-14) -3*a(n-15) -3*a(n-16) -3*a(n-17) -a(n-18) -a(n-19) for n>23
Comments