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A007390 Number of strict (-1)st-order maximal independent sets in cycle graph.
(Formerly M3257)
0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

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

Table of n, a(n) for n=1..37.

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)

CROSSREFS

Sequence in context: A002509 A230983 A100234 * A037955 A225121 A267991

Adjacent sequences:  A007387 A007388 A007389 * A007391 A007392 A007393

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Mira Bernstein

EXTENSIONS

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

STATUS

approved

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Last modified August 1 17:43 EDT 2021. Contains 346402 sequences. (Running on oeis4.)