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A155199 a(n)=10*a(n-1)+a(n-2), n>2 ; a(0)=1, a(1)=9, a(2)=90 . 1
1, 9, 90, 909, 9180, 92709, 936270, 9455409, 95490360, 964359009, 9739080450, 98355163509, 993290715540, 10031262318909, 101305913904630, 1023090401365209, 10332209927556720, 104345189676932409 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

FORMULA

G.f.: (1-x-x^2)/(1-10*x-x^2).

a(n) = (9/2)*((5+sqrt(26))^(n-1)+(5-sqrt(26))^(n-1))+(45/52)*sqrt(26)*((5+sqrt(26))^(n-1)-(5-sqrt(26))^(n-1))+(C(2*n,n) mod 2). - Paolo P. Lava, Jan 26 2009

a(n) = Sum_{k, 0<=k<=n} A155161(n,k)*9^k. - Philippe Deléham, Feb 08 2012

CROSSREFS

Sequence in context: A299872 A173480 A052268 * A147841 A036258 A098399

Adjacent sequences:  A155196 A155197 A155198 * A155200 A155201 A155202

KEYWORD

nonn,easy

AUTHOR

Philippe Deléham, Jan 21 2009

STATUS

approved

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Last modified May 16 15:55 EDT 2021. Contains 343949 sequences. (Running on oeis4.)