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A133646 a(n)=5*a(n-1)+30*a(n-2) for n>=3, a(0)=1, a(1)=5, a(2)=50 . 2
1, 5, 50, 400, 3500, 29500, 252500, 2147500, 18312500, 155987500, 1329312500, 11326187500, 96510312500, 822337187500, 7006995312500, 59705092187500, 508735320312500, 4334829367187500, 36936206445312500, 314725913242187500 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

FORMULA

G.f.: (1-5*x^2)/(1-5*x-30*x^2) . a(n) = Sum_{k, 0<=k<=n}A122950(n,k)*5^k .

a(n)=(5/2)*[(5/2)-(1/2)*sqrt(145)]^(n-1)-(15/58)*[(5/2)-(1/2)*sqrt(145)]^(n-1)*sqrt(145)+(15/58)*sqrt(145) *[(5/2)+(1/2)*sqrt(145)]^(n-1)+(5/2)*[(5/2)+(1/2)*sqrt(145)]^(n-1)+(1/6)*[C(2*n,n) mod 2], with n>=0

CROSSREFS

Sequence in context: A227261 A036291 A060347 * A043032 A247771 A125962

Adjacent sequences:  A133643 A133644 A133645 * A133647 A133648 A133649

KEYWORD

easy,nonn

AUTHOR

Philippe Deléham, Dec 31 2007

EXTENSIONS

Corrected formula. - Paolo P. Lava, Nov 24 2008

STATUS

approved

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Last modified August 14 09:14 EDT 2020. Contains 336480 sequences. (Running on oeis4.)