A007390 Number of strict (-1)st-order maximal independent sets in cycle graph.

0, 0, 0, 4, 5, 15, 21, 44, 66, 120, 187, 319, 507, 840, 1348, 2204, 3553, 5775, 9329, 15124, 24454, 39600, 64055, 103679, 167735, 271440, 439176, 710644, 1149821, 1860495, 3010317, 4870844, 7881162, 12752040, 20633203, 33385279, 54018483

Offset: 1

Author

N. J. A. Sloane, Mira Bernstein

Keywords

• nonn

References

• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
• R. Yanco and A. Bagchi, ``K-th order maximal independent sets in path and cycle graphs,'' J. Graph Theory, submitted, 1994.

Links

• R. Yanco, Letter and Email to N. J. A. Sloane, 1994

Formula

a(n) = A000204(n) - b(n) where b(1) = 1, b(2*n+1) = 2*n+2, b(2*n) = 3. - Sean A. Irvine, Jan 02 2018

Conjectures from Colin Barker, Jun 14 2019: (Start)

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

a(n) = a(n-1) + 3*a(n-2) - 2*a(n-3) - 3*a(n-4) + a(n-5) + a(n-6) for n>7.

(End)

Extensions

a(18) corrected and more terms from Sean A. Irvine, Jan 02 2018