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URL: https://oeis.org/A349333

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A349333
G.f. A(x) satisfies A(x) = 1 + x * A(x)^6 / (1 - x).
13
1, 1, 7, 64, 678, 7836, 95838, 1219527, 15979551, 214151601, 2921712145, 40444378948, 566634504256, 8019501351103, 114484746457075, 1646614155398872, 23837794992712680, 347081039681365623, 5079306905986689309, 74670702678690897079, 1102218694940440851877
OFFSET
0,3
LINKS
FORMULA
a(n) = Sum_{k=0..n} binomial(n-1,k-1) * binomial(6*k,k) / (5*k+1).
a(n) ~ 49781^(n + 1/2) / (72 * sqrt(3*Pi) * n^(3/2) * 5^(5*n + 3/2)). - Vaclav Kotesovec, Nov 15 2021
G.f.: 1 + Series_Reversion( x / (x+(1+x)^6) ). - Seiichi Manyama, Sep 29 2025
MAPLE
a:= n-> coeff(series(RootOf(1+x*A^6/(1-x)-A, A), x, n+1), x, n):
seq(a(n), n=0..20); # Alois P. Heinz, Nov 15 2021
MATHEMATICA
nmax = 20; A[_] = 0; Do[A[x_] = 1 + x A[x]^6/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
Table[Sum[Binomial[n - 1, k - 1] Binomial[6 k, k]/(5 k + 1), {k, 0, n}], {n, 0, 20}]
PROG
(PARI) {a(n) = my(A=[1]); for(m=1, n, A=concat(A, 0);
A[#A] = 1 + sum(k=1, m-1, (polcoeff(Ser(A)^6, k)) )); A[n+1]}
for(n=0, 30, print1(a(n), ", ")) \\ Vaclav Kotesovec, Nov 23 2024, after Paul D. Hanna
CROSSREFS
Cf. A002295, A346648 (partial sums), A349362.
Sequence in context: A362726 A371404 A213515 * A293470 A256506 A008787
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Nov 15 2021
STATUS
approved