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A296550
Number of n X 4 0..1 arrays with each 1 horizontally, vertically or antidiagonally adjacent to 3 or 6 neighboring 1s.
1
1, 1, 3, 5, 7, 10, 17, 28, 43, 66, 105, 168, 264, 413, 651, 1030, 1624, 2555, 4025, 6349, 10010, 15771, 24851, 39173, 61748, 97315, 153366, 241722, 380989, 600470, 946375, 1491567, 2350860, 3705166, 5839638, 9203761, 14505951, 22862658, 36033501
OFFSET
1,3
COMMENTS
Appears to be the number of tilings of a 7 X 2n rectangle with 7 X 1 heptominoes. - M. Poyraz Torcuk, Dec 25 2021
LINKS
FORMULA
Empirical: a(n) = a(n-1) + 2*a(n-4) + a(n-7).
Empirical g.f.: x*(1 + 2*x^2 + 2*x^3 + x^5 + x^6) / (1 - x - 2*x^4 - x^7). - Colin Barker, Feb 23 2019
EXAMPLE
Some solutions for n=7:
0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0
0 1 1 1 0 0 0 0 0 1 1 0 0 0 0 0 1 1 1 0
0 1 1 0 0 0 0 0 1 1 1 0 0 0 0 0 1 1 0 0
0 0 0 0 0 1 1 0 1 1 0 0 0 0 0 0 0 0 0 0
0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
CROSSREFS
Column 4 of A296554.
Sequence in context: A310023 A310024 A088635 * A031255 A376786 A335301
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 15 2017
STATUS
approved