A242795 a(n) = [x^n] ( 1 + x*A(x)^(n+1) )^(n+1) / (n+1) for n>=0, with a(0)=1.

1, 1, 4, 35, 466, 8072, 168330, 4045603, 109089538, 3242538284, 104946776716, 3665946814257, 137291732981170, 5483948111154008, 232660368810666229, 10447887814670412307, 495139557493903545618, 24699919104193662112382, 1293980412831022073519196

Offset

0,3

Comments

Compare to the g.f. G(x) = x + x*G(G(x)) of A030266 that satisfies:

A030266(n+1) = [x^n] ( 1 + G(x) )^(n+1) / (n+1) for n>=0.

Links

Table of n, a(n) for n=0..18.

Example

G.f.: A(x) = 1 + x + 4*x^2 + 35*x^3 + 466*x^4 + 8072*x^5 + 168330*x^6 +...
Form a table of coefficients of x^k in (1 + x*A(x)^(n+1))^(n+1) like so:
n=0: [1,  1,   1,    4,    35,    466,    8072,   168330, ...];
n=1: [1,  2,   5,   22,   178,   2228,   37141,   755702, ...];
n=2: [1,  3,  12,   64,   516,   6126,   97725,  1929927, ...];
n=3: [1,  4,  22,  140,  1177,  13548,  206876,  3946612, ...];
n=4: [1,  5,  35,  260,  2330,  26626,  391830,  7202170, ...];
n=5: [1,  6,  51,  434,  4185,  48432,  694714, 12312642, ...];
n=6: [1,  7,  70,  672,  6993,  83174, 1178310, 20224653, ...];
n=7: [1,  8,  92,  984, 11046, 136392, 1932876, 32364824, ...];
n=8: [1,  9, 117, 1380, 16677, 215154, 3084024, 50833962, ...];
n=9: [1, 10, 145, 1870, 24260, 328252, 4801655, 78652350, ...]; ...
then this sequence is formed from the main diagonal:
[1/1, 2/2, 12/3, 140/4, 2330/5, 48432/6, 1178310/7, 32364824/8, ...].

Prog

(PARI) {a(n)=local(A=[1, 1]); for(m=1, n, A=concat(A, 0); A[m+1]=Vec((1+x*Ser(A)^(m+1))^(m+1))[m+1]/(m+1)); A[n+1]}
for(n=0, 25, print1(a(n), ", "))

Crossrefs

Cf. A242794.

Sequence in context: A270917 A367925 A367923 * A349527 A287886 A342207

Adjacent sequences: A242792 A242793 A242794 * A242796 A242797 A242798

Keyword

nonn

Author

Paul D. Hanna, May 22 2014

Status

approved