A360338 G.f. A(x) satisfies: [x^n] A(x)^(n+1) = [x^n] (1 + x*A(x)^(3*n+2))^(n+1) for n >= 0.

1, 1, 8, 152, 4452, 169952, 7807014, 413004366, 24498135084, 1601156353073, 113923669100054, 8747479687135221, 720094655642863843, 63228142773931718867, 5897275794731167406208, 582262196337324537825772, 60678076577289308772410092, 6656827638797910274281675184

Offset

0,3

Links

Paul D. Hanna, Table of n, a(n) for n = 0..300

Formula

G.f. A(x) = Sum_{n>=0} a(n)*x^n satisfies:

(1) [x^n] A(x)^(n+1) = [x^n] (1 + x*A(x)^(3*n+2))^(n+1) for n>=0.

(2) A(x) = Sum_{n>=0} b(n) * x^n/A(x)^n, where b(n) = [x^n] (1 + x*A(x)^(3*n+2))^(n+1) / (n+1).

a(n) ~ c * d^n * n! * n^alpha, where d = 5.7189630165873859806..., alpha = 1.7741677239019..., c = 0.0189263625965882... - Vaclav Kotesovec, Feb 06 2023

Example

G.f.: A(x) = 1 + x + 8*x^2 + 152*x^3 + 4452*x^4 + 169952*x^5 + 7807014*x^6 + 413004366*x^7 + 24498135084*x^8 + 1601156353073*x^9 + ...
RELATED SERIES.
G.f. A(x) = B(x/A(x)) where B(x) = B(x*A(x)) begins:
B(x) = 1 + x + 9*x^2 + 177*x^3 + 5237*x^4 + 200533*x^5 + 9220635*x^6 + 487973429*x^7 + 28953420029*x^8 + ... + b(n)*x^n + ...
such that b(n) = [x^n] (1 + x*A(x)^(3*n+2))^(n+1) / (n+1),
as well as b(n) = [x^n] A(x)^(n+1) / (n+1),
so that b(n) begin:
[1/1, 2/2, 27/3, 708/4, 26185/5, 1203198/6, 64544445/7, 3903787432/8, ...].
ILLUSTRATION OF DEFINITION.
The table of coefficients of x^k in A(x)^(n+1) begins:
n=0: [1, 1,  8,  152,  4452,  169952,  7807014,  413004366, ...];
n=1: [1, 2, 17,  320,  9272,  351240, 16048268,  845695400, ...];
n=2: [1, 3, 27,  505, 14484,  544512, 24744926, 1298895150, ...];
n=3: [1, 4, 38,  708, 20113,  750448, 33919144, 1773460112, ...];
n=4: [1, 5, 50,  930, 26185,  969761, 43594110, 2270282630, ...];
n=5: [1, 6, 63, 1172, 32727, 1203198, 53794085, 2790292344, ...];
n=6: [1, 7, 77, 1435, 39767, 1451541, 64544445, 3334457687, ...];
n=7: [1, 8, 92, 1720, 47334, 1715608, 75871724, 3903787432, ...]; ...
Compare to the table of coefficients in (1 + x*A(x)^(3*n+2))^(n+1):
n=0: [1, 1,   2,   17,    320,    9272,    351240,   16048268, ...];
n=1: [1, 2,  11,  110,   1985,   54730,   2003692,   89482592, ...];
n=2: [1, 3,  27,  325,   5928,  157206,   5548868,  241397910, ...];
n=3: [1, 4,  50,  708,  13443,  348700,  11883916,  502177632, ...];
n=4: [1, 5,  80, 1305,  26185,  675816,  22359050,  916389110, ...];
n=5: [1, 6, 117, 2162,  46170, 1203198,  38962709, 1549794426, ...];
n=6: [1, 7, 161, 3325,  75775, 2016966,  64544445, 2498939864, ...];
n=7: [1, 8, 212, 4840, 117738, 3228152, 103075540, 3903787432, ...]; ...
to see that the main diagonals of the tables are the same.

Prog

(PARI) {a(n) = my(A=[1]); for(m=1, n, A=concat(A, 0); A[m+1] = (Vec((1+x*Ser(A)^(3*m+2))^(m+1))[m+1] - Vec(Ser(A)^(m+1))[m+1])/(m+1) ); A[n+1]}
for(n=0, 20, print1(a(n), ", "))

Crossrefs

Cf. A360336, A360337, A360234, A360346.

Sequence in context: A249931 A123770 A003400 * A059510 A264708 A094059

Adjacent sequences: A360335 A360336 A360337 * A360339 A360340 A360341

Keyword

nonn

Author

Paul D. Hanna, Feb 06 2023

Status

approved