A143435 G.f. A(x) satisfies A(x) = 1 + x*A(x*A(x))^3.

1, 1, 3, 15, 97, 738, 6297, 58630, 585543, 6200916, 69071103, 804470751, 9753459717, 122670681073, 1596129692136, 21437840848440, 296680980737270, 4224090724829151, 61794432127467450, 927795254532531834, 14282871462981487854, 225247807261125989496, 3636185180695164503129

Offset

0,3

Links

Table of n, a(n) for n=0..22.

Formula

G.f. satisfies: x - G(x) = G(x)^2*A(x)^3 where G(x*A) = x.

G.f. satisfies: A(x) = exp( Sum_{n>=0} [d^n/dx^n x^(2n+1)*A(x)^(3*n+3)]*A(x)^(-2n-2)/(n+1)! ). - Paul D. Hanna, Dec 18 2010

From Seiichi Manyama, Jun 05 2025: (Start)

Let a(n,k) = [x^n] A(x)^k.

a(n,0) = 0^n; a(n,k) = k * Sum_{j=0..n} binomial(n-j+k,j)/(n-j+k) * a(n-j,3*j). (End)

Example

G.f.: A(x) = 1 + x + 3*x^2 + 15*x^3 + 97*x^4 + 738*x^5 + 6297*x^6 +...
A(x*A(x)) = 1 + x + 4*x^2 + 24*x^3 + 178*x^4 + 1511*x^5 + 14130*x^6 +...
A(x*A(x))^3 = 1 + 3*x + 15*x^2 + 97*x^3 + 738*x^4 + 6297*x^5 +...
Logarithmic series:
log(A(x)) = x*A(x) + [d/dx x^3*A(x)^6]*A(x)^(-4)/2! + [d^2/dx^2 x^5*A(x)^9]*A(x)^(-6)/3! + [d^3/dx^3 x^7*A(x)^12]*A(x)^(-8)/4! +...

Prog

(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=1+x*subst(A^3, x, x*A)); polcoeff(A, n)}
(PARI) /* n-th Derivative: */
{Dx(n, F)=local(D=F); for(i=1, n, D=deriv(D)); D}
/* G.f.: Paul D. Hanna, Dec 18 2010 */
{a(n)=local(A=1+x+x*O(x^n)); for(i=1, n,
A=exp(sum(m=0, n, Dx(m, x^(2*m+1)*A^(3*m+3))*A^(-2*m-2)/(m+1)!)+x*O(x^n))); polcoeff(A, n)}
(PARI) a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(n-j+k, j)/(n-j+k)*a(n-j, 3*j))); \\ Seiichi Manyama, Jun 05 2025

Crossrefs

Cf. A143426, A143436, A143437.

Cf. A139702, A087949, A182969.

Sequence in context: A378882 A108442 A060148 * A331325 A132437 A331610

Adjacent sequences: A143432 A143433 A143434 * A143436 A143437 A143438

Keyword

nonn

Author

Paul D. Hanna, Aug 14 2008

Status

approved