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A185010
a(n) = A000108(n)*A015518(n+1), where A000108 are the Catalan numbers and A015518(n) = 2*A015518(n-1) + 3*A015518(n-2).
1
1, 2, 14, 100, 854, 7644, 72204, 703560, 7037030, 71772844, 743844452, 7810307960, 82909630972, 888316731800, 9593823377880, 104332819539600, 1141523825614470, 12556761952114380, 138785264158902900, 1540516430396559000, 17165754516697206420, 191944345934966132040
OFFSET
0,2
COMMENTS
More generally, given {S} such that: S(n) = b*S(n-1) + c*S(n-2), |b|>0, |c|>0, S(0)=1, then
Sum_{n>=0} S(n)*Catalan(n)*x^n = sqrt( (1-2*b*x - sqrt(1-4*b*x-16*c*x^2))/(2*b^2+8*c) )/x.
FORMULA
G.f.: sqrt( (1-4*x - sqrt(1-8*x-48*x^2))/32 )/x.
G.f.: sqrt( M(4*x) ), where M(x) is g.f. of A001006. - Werner Schulte, Aug 10 2015
Conjecture: n*(n+1)*a(n) -4*n*(2*n-1)*a(n-1) -12*(2*n-1)*(2*n-3)*a(n-2)=0. - R. J. Mathar, Oct 08 2016
G.f: B(m(4z)/4), where B(x) is the g.f. of A000984 and m(x) is the g.f. of A086246. - Alexander Burstein, May 20 2021
EXAMPLE
G.f.: A(x) = 1 + 1*2*x + 2*7*x^2 + 5*20*x^3 + 14*61*x^4 + 42*182*x^5 + 132*547*x^6 +...+ A000108(n)*A015518(n+1)*x^n +...
MATHEMATICA
CoefficientList[Series[Sqrt[(1 - 4*x - Sqrt[1 - 8*x - 48*x^2])/32]/x, {x, 0, 50}], x] (* G. C. Greubel, Jun 09 2017 *)
PROG
(PARI) {A000108(n)=binomial(2*n, n)/(n+1)}
{A015518(n)=polcoeff(x/(1-2*x-3*x^2 +x*O(x^n)), n)}
{a(n)=A000108(n)*A015518(n+1)}
for(n=0, 30, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Dec 26 2012
STATUS
approved