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A155127 a(n)=6*a(n-1)+6*a(n-2), n>2 ; a(0)=1, a(1)=5, a(2)=35 . 1
1, 5, 35, 240, 1650, 11340, 77940, 535680, 3681720, 25304400, 173916720, 1195326720, 8215460640, 56464724160, 388081108800, 2667274997760, 18332136639360, 125996469822720, 865971638772480, 5951808651571200 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..19.

Index entries for linear recurrences with constant coefficients, signature (6,6).

FORMULA

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

a(n)=(2/3)*sqrt(15)*{[3+sqrt(15)]^(n-1)-[3-sqrt(15)]^(n-1)}+(5/2)*{[3+sqrt(15)]^(n-1)+[3-sqrt(15)]^(n-1)}+(1/6)*[C(2*n,n) mod 2], with n>=0 [From Paolo P. Lava, Jan 26 2009]

MATHEMATICA

LinearRecurrence[{6, 6}, {1, 5, 35}, 20] (* Harvey P. Dale, Apr 14 2015 *)

CROSSREFS

Sequence in context: A091928 A305739 A290903 * A239846 A193577 A196661

Adjacent sequences:  A155124 A155125 A155126 * A155128 A155129 A155130

KEYWORD

nonn

AUTHOR

Philippe Deléham, Jan 20 2009

STATUS

approved

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Last modified February 22 23:44 EST 2020. Contains 332157 sequences. (Running on oeis4.)