A332348 Number of maximal independent sets in the 3 X n king graph.

1, 2, 6, 8, 22, 40, 82, 176, 340, 722, 1450, 2966, 6096, 12362, 25384, 51728, 105698, 216074, 440962, 901396, 1840686, 3760232, 7681828, 15689962, 32053346, 65473214, 133745304, 273208346, 558081744, 1140024080, 2328745042, 4757002434, 9717279194, 19849727740

Offset: 0

Author

Andrew Howroyd, Feb 10 2020

Keywords

• nonn
• easy

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..500
• Index entries for linear recurrences with constant coefficients, signature (1,2,1,-2,2,-2).

Crossrefs

Row n=3 of A332347.

Programs

PARI

Vec((1 + x + 2*x^2 - 3*x^3 + 2*x^4 - 2*x^5)/(1 - x - 2*x^2 - x^3 + 2*x^4 - 2*x^5 + 2*x^6) + O(x^40))

Formula

a(n) = a(n-1) + 2*a(n-2) + a(n-3) - 2*a(n-4) + 2*a(n-5) - 2*a(n-6) for n >= 6.

G.f.: (1 + x + 2*x^2 - 3*x^3 + 2*x^4 - 2*x^5)/(1 - x - 2*x^2 - x^3 + 2*x^4 - 2*x^5 + 2*x^6).