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A295601
Number of n X 3 0..1 arrays with each 1 horizontally or vertically adjacent to 0, 2, 3 or 4 1s.
1
5, 20, 83, 338, 1425, 6080, 26249, 114298, 501405, 2211832, 9799095, 43554852, 194071913, 866357594, 3872915901, 17331341902, 77618369051, 347815345000, 1559266623743, 6992481752642, 31365036076887, 140713926545922
OFFSET
1,1
COMMENTS
Column 3 of A295606.
FORMULA
Empirical: a(n) = 7*a(n-1) - 9*a(n-2) - 11*a(n-3) + 14*a(n-4) - 53*a(n-5) + 19*a(n-6) + 42*a(n-7) - 23*a(n-8) + 72*a(n-9) + 36*a(n-10) - 25*a(n-11) - 12*a(n-12).
Formula confirmed by Robert Israel, Nov 24 2017 (see link).
EXAMPLE
Some solutions for n=7:
0 0 0 0 0 1 0 1 0 0 0 0 0 0 1 1 0 0 0 1 0
1 1 0 0 1 0 0 0 1 0 0 1 1 0 0 0 0 0 1 0 0
1 1 1 0 0 1 0 0 0 0 1 0 0 1 0 1 0 0 0 1 0
1 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 0 0
0 0 0 1 1 0 1 1 1 0 0 0 0 1 0 0 1 1 0 0 0
0 0 1 1 1 0 1 0 1 1 0 0 0 0 0 0 1 1 0 0 1
0 0 0 0 0 0 1 1 1 0 0 1 1 0 1 0 1 1 1 0 0
CROSSREFS
Cf. A295606.
Sequence in context: A030520 A183933 A323262 * A301946 A292760 A270322
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 24 2017
STATUS
approved