Search: id:A137972
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%I A137972
%S A137972 1,1,6,39,320,2787,25788,247731,2449188,24753960,254610962,2656496133,
%T A137972 28046838948,299085697722,3216723340218,34852657892685,380063012970680,
%U A137972 4168108473073596,45941874232280862,508664757809869052
%N A137972 G.f. satisfies A(x) = 1 + x*(1 + x*A(x)^4)^6.
%F A137972 G.f.: A(x) = 1 + x*B(x)^6 where B(x) is the g.f. of A137971.
%F A137972 a(n) = Sum_{k=0..n-1} C(6*(n-k),k)/(n-k) * C(4*k,n-k-1) for n>0 with 
               a(0)=1. [From Paul D. Hanna (pauldhanna(AT)juno.com), Jun 16 2009]
%o A137972 (PARI) {a(n)=local(A=1+x*O(x^n));for(i=0,n,A=1+x*(1+x*A^4)^6);polcoeff(A,
               n)}
%o A137972 (PARI) a(n)=if(n==0,1,sum(k=0,n-1,binomial(6*(n-k),k)/(n-k)*binomial(4*k,
               n-k-1))) [From Paul D. Hanna (pauldhanna(AT)juno.com), Jun 16 2009]
%Y A137972 Cf. A137971, A137973; A137968, A137970, A137974.
%Y A137972 Sequence in context: A009018 A135890 A067273 this_sequence A007322 A058191 
               A113347
%Y A137972 Adjacent sequences: A137969 A137970 A137971 this_sequence A137973 A137974 
               A137975
%K A137972 nonn
%O A137972 0,3
%A A137972 Paul D. Hanna (pauldhanna(AT)juno.com), Feb 26 2008

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