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A332349
Number of maximal independent sets in the 4 X n king graph.
2
1, 3, 12, 22, 79, 194, 537, 1519, 4011, 11258, 30506, 83661, 229754, 627171, 1721547, 4710045, 12901630, 35342272, 96764537, 265067580, 725878627, 1988023833, 5444771405, 14911382924, 40839083772, 111846316151, 306317816028, 838924085421, 2297583803229, 6292480053823
OFFSET
0,2
FORMULA
a(n) = a(n-1) + 4*a(n-2) + 3*a(n-3) - 4*a(n-4) + 6*a(n-5) - 3*a(n-6) - 6*a(n-7) for n >= 7.
G.f.: (1 + 2*x + 5*x^2 - 5*x^3 + 4*x^4 - 3*x^5 - 6*x^6)/((1 - x)*(1 - 4*x^2 - 7*x^3 - 3*x^4 - 9*x^5 - 6*x^6)).
PROG
(PARI) Vec((1 + 2*x + 5*x^2 - 5*x^3 + 4*x^4 - 3*x^5 - 6*x^6)/((1 - x)*(1 - 4*x^2 - 7*x^3 - 3*x^4 - 9*x^5 - 6*x^6)) + O(x^40))
CROSSREFS
Row n=4 of A332347.
Sequence in context: A015629 A341374 A154138 * A354529 A242636 A012469
KEYWORD
nonn,easy
AUTHOR
Andrew Howroyd, Feb 10 2020
STATUS
approved