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A027266 a(n) = Sum_{k=0..2n} (k+1) * A026519(n, k). 0
1, 6, 18, 72, 180, 648, 1512, 5184, 11664, 38880, 85536, 279936, 606528, 1959552, 4199040, 13436928, 28553472, 90699264, 191476224, 604661760, 1269789696, 3990767616, 8344332288, 26121388032, 54419558400, 169789022208 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..25.

Index entries for linear recurrences with constant coefficients, signature (0,12,0,-36).

FORMULA

G.f.: (1+6x+6x^2)/(1-6x^2)^2.

a(0)=1, a(1)=6, a(2)=18, a(3)=72, a(n)=12*a(n-2)-36*a(n-4). - Harvey P. Dale, Jun 19 2015

MATHEMATICA

CoefficientList[Series[(1+6x+6x^2)/(1-6x^2)^2, {x, 0, 30}], x] (* or *) LinearRecurrence[{0, 12, 0, -36}, {1, 6, 18, 72}, 30] (* Harvey P. Dale, Jun 19 2015 *)

CROSSREFS

Sequence in context: A304941 A129369 A095853 * A242278 A129796 A129790

Adjacent sequences:  A027263 A027264 A027265 * A027267 A027268 A027269

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified June 15 21:52 EDT 2021. Contains 345053 sequences. (Running on oeis4.)