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%I #8 Dec 30 2015 03:56:53
%S 1,1,13,415,22321,1721101,174252997,21935478979,3308902366945,
%T 582483654850105,117302814498577501,26610247617703733479,
%U 6716634535536518884177,1867456548257171896034245,567177496490226897535216405,186852683125922747089699211851,66371163246016212237620717414593,25287323016605747194753141853886961,10287301449354981886046538248627595565,4450859089975905722184296672608494825775,2040775907870521098252331495354110194770801
%N E.g.f.: Limit_{N->oo} [ Sum_{n>=0} (N + 3*n)^(2*n) * (x/N)^n/n! ]^(1/N).
%C Compare to: Limit_{N->oo} [ Sum_{n>=0} (N + n)^n * x^n/n! ]^(1/N) = Sum_{n>=0} (n+1)^(n-1) * x^n/n!.
%e E.g.f.: A(x) = 1 + x + 13*x^2/2! + 415*x^3/3! + 22321*x^4/4! + 1721101*x^5/5! + 174252997*x^6/6! + 21935478979*x^7/7! + 3308902366945*x^8/8! + 582483654850105*x^9/9! + 117302814498577501*x^10/10! +...
%e where A(x) equals the limit, as N -> oo, of the series
%e [1 + (N+3)^2*(x/N) + (N+6)^4*(x/N)^2/2! + (N+9)^6*(x/N)^3/3! + (N+12)^8*(x/N)^4/4! + (N+15)^10*(x/N)^5/5! + (N+18)^12*(x/N)^6/6! +...]^(1/N).
%o (PARI) /* Informal listing of terms 0..30 */
%o \p300
%o P(n) = sum(k=0,32, (n+3*k)^(2*k) * x^k/k! +O(x^32))
%o Vec( round( serlaplace( subst(P(10^100)^(1/10^100),x,x/10^100) )*1.) )
%Y Cf. A266481, A266482, A266483, A266484, A266485, A266487.
%K nonn
%O 0,3
%A _Paul D. Hanna_, Dec 30 2015