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A295168 Chromatic invariant of the 2n-crossed prism graph. 0
1, 11, 85, 521, 2869, 15017, 76717, 387425, 1945957, 9749753, 48793309, 244064849, 1220539285, 6103163369, 30516824461, 152586284993, 762936045253, 3814690056665, 19073471123773, 95367399659057, 476837091094261, 2384185650506441, 11920928661476845 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Extended to a(1) using formula/recurrence.

LINKS

Table of n, a(n) for n=1..23.

Eric Weisstein's World of Mathematics, Chromatic Invariant

Eric Weisstein's World of Mathematics, Crossed Prism Graph

Index entries for linear recurrences with constant coefficients, signature (9, -24, 20).

FORMULA

a(n) = 5^n - 2^(n - 1)*(3*n + 1).

a(n) = 9*a(n-1) - 24*a(n-2) + 20*a(n-3).

G.f. = x*(-1 - 2*x - 10*x^2)/((-1 + 2*x)^2 (-1 + 5*x)).

MATHEMATICA

Table[5^n - 2^(n - 1) (3 n + 1), {n, 20}]

LinearRecurrence[{9, -24, 20}, {1, 11, 85}, 20]

CoefficientList[Series[(-1 - 2 x - 10 x^2)/((-1 + 2 x)^2 (-1 + 5 x)), {x, 0, 20}], x]

CROSSREFS

Sequence in context: A026783 A244975 A271558 * A001240 A129180 A082365

Adjacent sequences:  A295165 A295166 A295167 * A295169 A295170 A295171

KEYWORD

nonn,easy

AUTHOR

Eric W. Weisstein, Nov 16 2017

STATUS

approved

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Last modified October 23 21:27 EDT 2021. Contains 348217 sequences. (Running on oeis4.)