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 A153397 G.f.: A(x) = F(x*G(x)^4) = F(G(x)-1) where F(x) = G(x/F(x)^2) = 1 + x*F(x)^2 is the g.f. of A000108 (Catalan) and G(x) = F(x*G(x)^2) = 1 + x*G(x)^4 is the g.f. of A002293. 2
 1, 1, 6, 43, 334, 2717, 22776, 195000, 1695874, 14927990, 132673398, 1188412986, 10714602196, 97133633788, 884716464592, 8091061578807, 74259516900390, 683694381314696, 6312247839166260, 58424001667319720, 541971167468786770 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS FORMULA a(n) = Sum_{k=0..n} C(2k+1,k)/(2k+1) * C(4n,n-k)*k/n for n>0 with a(0)=1. G.f. satisfies: A(x) = 1 + x*G(x)^4*A(x)^2 where G(x) is the g.f. of A002293. G.f. satisfies: A(x/F(x)^2) = F(F(x)-1) where F(x) is the g.f. of A000108. G.f. satisfies: A(x/H(x)) = F(H(x)-1) where H(x) = 1 + x*H(x)^3 is the g.f. of A001764 and F(x) is the g.f. of A000108. EXAMPLE G.f.: A(x) = F(x*G(x)^4) = 1 + x + 6*x^2 + 43*x^3 + 334*x^4 +... F(x) = 1 + x + 2*x^2 + 5*x^3 + 14*x^4 + 42*x^5 + 132*x^6 +... F(x)^2 = 1 + 2*x + 5*x^2 + 14*x^3 + 42*x^4 + 132*x^5 + 429*x^6 +... G(x) = 1 + x + 4*x^2 + 22*x^3 + 140*x^4 + 969*x^5 + 7084*x^6 +... G(x)^2 = 1 + 2*x + 9*x^2 + 52*x^3 + 340*x^4 + 2394*x^5 +... G(x)^3 = 1 + 3*x + 15*x^2 + 91*x^3 + 612*x^4 + 4389*x^5 +... G(x)^4 = 1 + 4*x + 22*x^2 + 140*x^3 + 969*x^4 + 7084*x^5 +... A(x)^2 = 1 + 2*x + 13*x^2 + 98*x^3 + 790*x^4 + 6618*x^5 +... G(x)^4*A(x)^2 = 1 + 6*x + 43*x^2 + 334*x^3 + 2717*x^4 + 22776*x^5 +... PROG (PARI) {a(n)=if(n==0, 1, sum(k=0, n, binomial(2*k+1, k)/(2*k+1)*binomial(4*(n-k)+4*k, n-k)*4*k/(4*(n-k)+4*k)))} CROSSREFS Cf. A000108, A001764, A002293; A153396, A153398. Sequence in context: A349302 A025594 A098665 * A005786 A071541 A146966 Adjacent sequences:  A153394 A153395 A153396 * A153398 A153399 A153400 KEYWORD nonn AUTHOR Paul D. Hanna, Jan 15 2009 STATUS approved

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Last modified May 16 05:56 EDT 2022. Contains 353693 sequences. (Running on oeis4.)