A107589 G.f. satisfies: A(x) = 1 + Sum_{n>=1} x^n*A^(2^(n-1)).

1, 1, 2, 5, 15, 52, 205, 921, 4807, 30288, 243338, 2636799, 39930125, 851799936, 25433798924, 1055317281976, 60604557533320, 4808635126697325, 526853206940116357, 79701484897115170371, 16651360300285759198344

Offset

0,3

Links

Table of n, a(n) for n=0..20.

Example

A = 1 + x*A + x^2*A^2 + x^3*A^4 + x^4*A^8 + x^5*A^16 +...
= 1 + (x + x^2 + 2*x^3 + 5*x^4 + 15*x^5 + 52*x^6 +...)
+ (x^2 + 2*x^3 + 5*x^4 + 14*x^5 + 44*x^6 + 154*x^7 +...)
+ (x^3 + 4*x^4 + 14*x^5 + 48*x^6 + 169*x^7 +...)
+ (x^4 + 8*x^5 + 44*x^6 + 208*x^7 +...)
+ (x^5 + 16*x^6 + 152*x^7 +...) +...

Prog

(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(k=1, n, A=1+sum(j=1, n, x^j*A^(2^(j-1)))); polcoeff(A, n)}

Crossrefs

Sequence in context: A336021 A186001 A134381 * A249892 A352853 A006790

Adjacent sequences: A107586 A107587 A107588 * A107590 A107591 A107592

Keyword

nonn

Author

Paul D. Hanna, May 17 2005

Status

approved