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A165324 a(0)=1, a(1)=9, a(n)= 19*a(n-1)-81*a(n-2) for n>1. 2
1, 9, 90, 981, 11349, 136170, 1667961, 20661489, 257463450, 3218224941, 40291734429, 504866733930, 6328837455921, 79353706214169, 995084584139610, 12478956895304901, 156498329695484709, 1962672755694512490 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n)/a(n-1) tends to (19+sqrt(37))/2 = 12.5413812...

LINKS

Table of n, a(n) for n=0..17.

FORMULA

G.f.: (1-10x)/(1-19x+81x^2). a(n)= Sum_{k, 0<=k<=n}A165253(n,k)*9^(n-k).

a(n) = ((37-sqrt(37))*(19+sqrt(37))^n+(37+sqrt(37))*(19-sqrt(37))^n)/(74*2^n). [From Klaus Brockhaus, Sep 28 2009]

CROSSREFS

Sequence in context: A264914 A143079 A233829 * A082367 A276506 A049389

Adjacent sequences:  A165321 A165322 A165323 * A165325 A165326 A165327

KEYWORD

nonn

AUTHOR

Philippe Deléham, Sep 14 2009

STATUS

approved

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Last modified May 20 20:16 EDT 2019. Contains 323426 sequences. (Running on oeis4.)