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A043699 a(n)= A000129(n)*A000129(2*n) where A000129(n) are the Pell numbers. 0
0, 2, 24, 350, 4896, 68962, 970200, 13652158, 192099456, 2703046850, 38034749784, 535189557278, 7530688519200, 105964828904482, 1491038292992664, 20980500931258750, 295218051329511936, 4154033219547089282, 58451683124982331800, 822477596969315258078 (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 (12,30,-12,-1).

FORMULA

a(n) is asymptotic to (1/8)*(7+2*sqrt(5))^n.

a(n) = 2 * A052208(n).

G.f.: 2*x*(x^2+1) / ((x^2-2*x-1)*(x^2+14*x-1)). - Colin Barker, Oct 19 2013

PROG

(PARI) a(n)=if(n<0, 0, contfracpnqn(vector(n, i, 1+(i>1)))[2, 1]*contfracpnqn(vector (2*n, i, 1+(i>1)))[2, 1])

(PARI) Vec(2*x*(x^2+1)/((x^2-2*x-1)*(x^2+14*x-1)) + O(x^100)) \\ Colin Barker, Oct 19 2013

CROSSREFS

Cf. A000129.

Sequence in context: A209290 A333715 A081065 * A220317 A220340 A134805

Adjacent sequences: A043696 A043697 A043698 * A043700 A043701 A043702

KEYWORD

nonn,easy

AUTHOR

Gary W. Adamson, Feb 01 2000

STATUS

approved

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Last modified December 8 14:51 EST 2022. Contains 358695 sequences. (Running on oeis4.)