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A124462
Row 2 of rectangular table A124460.
8
1, 3, 8, 23, 73, 251, 919, 3549, 14371, 60720, 266481, 1209807, 5662008, 27238884, 134391046, 678739990, 3503708942, 18462855900, 99211177417, 543161148837, 3027439667989, 17167987227428, 98995692542858, 580166879766649
OFFSET
0,2
FORMULA
G.f.: A(x) = Sum_{n>=0} x^n*R_n(x)^2, where R_n(x) is the g.f. of row n in table A124460 and satisfies: R_n(x) = Sum_{k>=0} x^k * R_k(x)^n for n>=0.
PROG
(PARI) {a(n)=local(m=max(n, 2), R=vector(m+1, r, vector(m+1, c, binomial(r+c-2, c-1)))); for(i=0, m, for(r=0, m, R[r+1]=Vec(sum(c=0, m, x^c*Ser(R[c+1])^r+O(x^(m+1)))))); R[3][n+1]}
CROSSREFS
Cf. A124460 (table); other rows: A124461, A124463, A124464, A124465, A124466.
Sequence in context: A080410 A230952 A148777 * A047857 A101495 A134758
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 03 2006
STATUS
approved