login
A204751
Number of (n+2) X 7 0..1 arrays with every 3 X 3 subblock having three equal elements in a row horizontally, vertically, diagonally or antidiagonally exactly three ways, and new values 0..1 introduced in row major order.
1
342, 38, 35, 40, 48, 61, 82, 116, 171, 260, 404, 637, 1014, 1624, 2611, 4208, 6792, 10973, 17738, 28684, 46395, 75052, 121420, 196445, 317838, 514256, 832067, 1346296, 2178336, 3524605, 5702914, 9227492, 14930379, 24157844, 39088196
OFFSET
1,1
COMMENTS
Column 5 of A204754.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) - a(n-3) for n > 5.
Empirical g.f.: x*(342 - 646*x - 41*x^2 + 312*x^3 + 6*x^4) / ((1 - x)*(1 - x - x^2)). - Colin Barker, Jun 10 2018
EXAMPLE
Some solutions for n=3:
0 1 0 1 0 0 1 0 0 1 1 1 0 0 0 0 1 0 1 0 1
0 1 0 1 0 0 1 0 0 0 1 1 1 0 0 0 1 0 1 0 1
0 1 0 1 0 0 1 1 0 0 0 1 1 1 0 0 1 0 1 0 1
0 1 0 1 0 0 1 1 1 0 0 0 1 1 0 0 1 0 1 0 1
0 1 0 1 0 0 1 1 1 1 0 0 0 1 0 0 1 0 1 0 1
CROSSREFS
Cf. A204754.
Sequence in context: A328665 A163582 A239271 * A247441 A045106 A137201
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 18 2012
STATUS
approved