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A203808 G.f.: exp( Sum_{n>=1} A000204(n)^8 * x^n/n ) where A000204 is the Lucas numbers. 9

%I #13 Dec 26 2017 03:15:19

%S 1,1,3281,25126,6845526,121368902,12805025677,373879862237,

%T 24707348223677,948781359159752,50702478932197928,2210812262034197128,

%U 108528095366637700218,4974402150387759436378,236926456045384849970778,11047772769135934828000404

%N G.f.: exp( Sum_{n>=1} A000204(n)^8 * x^n/n ) where A000204 is the Lucas numbers.

%C More generally, exp(Sum_{k>=1} A000204(k)^(2*n) * x^k/k) = 1/(1 - (-1)^n*x)^binomial(2*n,n) * Product_{k=1..n} 1/(1 - (-1)^(n-k)*A000204(2*k)*x + x^2)^binomial(2*n,n-k).

%H G. C. Greubel, <a href="/A203808/b203808.txt">Table of n, a(n) for n = 0..596</a>

%F G.f.: 1/( (1-x)^70 * (1+3*x+x^2)^56 * (1-7*x+x^2)^28 * (1+18*x+x^2)^8 * (1-47*x+x^2) ).

%F G.f.: 1/Product_{n>=1} (1 - Lucas(n)*x^n + (-1)^n*x^(2*n))^A203858(n) where A203858(n) = (1/n)*Sum_{d|n} moebius(n/d)*Lucas(d)^7.

%e G.f.: A(x) = 1 + x + 3281*x^2 + 25126*x^3 + 6845526*x^4 + 121368902*x^5 + ...

%e where

%e log(A(x)) = x + 3^8*x^2/2 + 4^8*x^3/3 + 7^8*x^4/4 + 11^8*x^5/5 + 18^8*x^6/6 + 29^8*x^7/7 + 47^8*x^8/8 + ... + Lucas(n)^8*x^n/n + ...

%t CoefficientList[Series[1/((1 - x)^70*(1 + 3*x + x^2)^56*(1 - 7*x + x^2)^28*(1 + 18*x + x^2)^8*(1 - 47*x + x^2)), {x, 0, 50}], x] (* _G. C. Greubel_, Dec 25 2017 *)

%o (PARI) /* Subroutine used in PARI programs below: */

%o {Lucas(n)=fibonacci(n-1)+fibonacci(n+1)}

%o (PARI) {a(n)=polcoeff(exp(sum(k=1, n, Lucas(k)^8*x^k/k)+x*O(x^n)), n)}

%o (PARI) {a(n,m=4)=polcoeff(1/(1 - (-1)^m*x+x*O(x^n))^binomial(2*m,m) * prod(k=1,m,1/(1 - (-1)^(m-k)*Lucas(2*k)*x + x^2+x*O(x^n))^binomial(2*m,m-k)),n)}

%Y Cf. A002571, A203803, A203804, A203805, A203806, A203807, A203809.

%Y Cf. A203858, A203800.

%K nonn

%O 0,3

%A _Paul D. Hanna_, Jan 06 2012

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Last modified July 27 06:21 EDT 2024. Contains 374641 sequences. (Running on oeis4.)