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A297665
Number of chordless cycles in the n-web graph.
0
3, 10, 17, 26, 37, 54, 83, 132, 211, 336, 535, 856, 1377, 2222, 3589, 5798, 9369, 15146, 24495, 39624, 64103, 103708, 167787, 271468, 439229, 710674, 1149881, 1860530, 3010381, 4870878, 7881227, 12752076, 20633275, 33385320, 54018559, 87403840, 141422361, 228826166
OFFSET
3,1
LINKS
Eric Weisstein's World of Mathematics, Chordless Cycle
Eric Weisstein's World of Mathematics, Web Graph
FORMULA
a(n) = A000032(n) + A057079(n+1) + n for n >= 4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - 2*a(n-5) + a(n-6) for n >= 10.
G.f.: -x^3*(2*x^6 - 5*x^4 + 6*x^3 - 5*x^2 - 2*x + 3)/((x - 1)^2*(x^2 - x + 1)*(x^2 + x - 1)).
MATHEMATICA
LinearRecurrence[{4, -6, 4, 0, -2, 1}, {3, 10, 17, 26, 37, 54, 83}, 38]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Jan 02 2018
EXTENSIONS
Terms for n >= 9 corrected, and formulas and programs adjusted by Pontus von Brömssen, Nov 13 2022
STATUS
approved