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A027012 a(n) = T(2*n, n+1), T given by A027011. 1
1, 6, 47, 199, 661, 1954, 5442, 14696, 39065, 103025, 270655, 709716, 1859412, 4869594, 12750611, 33383659, 87401977, 228824086, 599072310, 1568395100, 4106115485, 10749954101, 28143749827, 73681298664, 192900149736, 505019154414, 1322157317687 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Colin Barker, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (6,-13,13,-6,1)

FORMULA

a(1)=1, a(n) = Lucas(2*n+6) - (6*n^2+17*n+18). - Ralf Stephan, May 05 2005

From Colin Barker, Feb 19 2016: (Start)

a(n) = -8 + (2^(-1-n)*((3-sqrt(5))^n*(-15+7*sqrt(5))+(3+sqrt(5))^n*(15+7*sqrt(5))))/sqrt(5) + 13*(1+n) - 6*(1+n)*(2+n) for n>1.

a(n) = 6*a(n-1)-13*a(n-2)+13*a(n-3)-6*a(n-4)+a(n-5) for n>6.

G.f.: x*(1+24*x^2-18*x^3+6*x^4-x^5) / ((1-x)^3*(1-3*x+x^2)).

(End)

MATHEMATICA

Join[{1}, LinearRecurrence[{6, -13, 13, -6, 1}, {6, 47, 199, 661, 1954}, 30]] (* Harvey P. Dale, Nov 17 2013 *)

PROG

(PARI) Vec(x*(1+24*x^2-18*x^3+6*x^4-x^5)/((1-x)^3*(1-3*x+x^2)) + O(x^40)) \\ Colin Barker, Feb 19 2016

CROSSREFS

Sequence in context: A184725 A232495 A267233 * A160609 A267203 A024076

Adjacent sequences:  A027009 A027010 A027011 * A027013 A027014 A027015

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling

EXTENSIONS

More terms from Harvey P. Dale, Nov 17 2013

STATUS

approved

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Last modified February 19 08:57 EST 2019. Contains 320309 sequences. (Running on oeis4.)