cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A156904 G.f. A(x) satisfies: A(x) = 1 + x*Sum_{n>=0} log( A(3^n*x) )^n / n!.

Original entry on oeis.org

1, 1, 3, 63, 6732, 3414312, 10221878106, 243813944182248, 50538758405328815616, 87376772859536771916909012, 1235009698863206337006094872463887, 142641072494398006081741872595533545306244
Offset: 0

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Author

Paul D. Hanna, Mar 04 2009

Keywords

Examples

			G.f.: A(x) = 1 + x + 3*x^2 + 63*x^3 + 6732*x^4 + 3414312*x^5 +...
SERIES REPRESENTATION:
A(x) = 1 + x*[1 + log(A(3x)) + log(A(9x))^2/2! + log(A(27x))^3/3! +...+ log(A(3^n*x))^n/n! +...].
...
GENERATED BY POWERS OF G.F.:
a(n+1) equals the coefficient of x^n in A(x)^(3^n) for n>=0;
the coefficients of A(x)^(3^n) begin:
A^(3^0): [(1), 1, 3, 63, 6732, 3414312, 10221878106, ...];
A^(3^1): [1, (3), 12, 208, 20610, 10284678, 30686274630, ...];
A^(3^2): [1, 9, (63), 867, 66330, 31246902, 92246164932, ...];
A^(3^3): [1, 27, 432, (6732), 273024, 97968096, 278472473082, ...];
A^(3^4): [1, 81, 3483, 109863, (3414312), 385422948, 853280745822, ...];
A^(3^5): [1, 243, 30132, 2553768, 168586110, (10221878106), ...];
In the above table, the diagonal forms this sequence shift left.
		

Crossrefs

Programs

  • PARI
    {a(n)=local(A=[1, 1]); for(i=1, n, A=concat(A, Vec(Ser(A)^(3^(#A-1)))[ #A])); A[n+1]}

Formula

G.f. A(x) satisfies: a(n+1) = [x^n] A(x)^(3^n) for n>=0, with a(0)=1.

A366226 O.g.f. A(x) satisfies: A(x) = 1 + x*Sum_{n>=0} 2^n * log( A(3^n*x) )^n / n!.

Original entry on oeis.org

1, 1, 6, 261, 56070, 56526498, 334429044030, 15777272891508021, 6500948711591606135796, 22416650201723925643982814186, 632905244163070372226486183732882316, 146120187946706698644410320973489902454862324, 277121097159744219425840626808464318501357604841881466
Offset: 0

Views

Author

Paul D. Hanna, Oct 16 2023

Keywords

Comments

In general, we have the following identity:
given A(x) = Sum_{n>=0} a(n)*x^n satisfies
A(x) = 1 + x*Sum_{n>=0} p^n * log( A(q^n*x) )^n / n!,
then a(n+1) = [x^n] A(x)^(p*q^n) for n >= 0, with a(0)=1,
for arbitrary fixed parameters p and q.
Here, p = 2 and q = 3.

Examples

			G.f.: A(x) = 1 + x + 6*x^2 + 261*x^3 + 56070*x^4 + 56526498*x^5 + 334429044030*x^6 + 15777272891508021*x^7 + 6500948711591606135796*x^8 + ...
where
A(x) = 1 + x*[1 + 2*log(A(3*x)) + 2^2*log(A(3^2*x))^2/2! + 2^3*log(A(3^2*x))^3/3! + ... + 2^n*log(A(3^n*x))^n/n! + ...].
RELATED SERIES.
log(A(x)) = x + 11*x^2/2 + 766*x^3/3 + 223187*x^4/4 + 282345766*x^5/5 + 2006233236098*x^6/6 + 110438567161208518*x^7/7 + ...
RELATED TABLE.
The table of coefficients of x^k in A(x)^(2*3^n) begins:
n=0: [1,   2,     13,      534,     112698,    113168268, ...];
n=1: [1,   6,     51,     1766,     345165,    340906254, ...];
n=2: [1,  18,    261,     7350,    1112382,   1035922644, ...];
n=3: [1,  54,   1755,    56070,    4589001,   3250238022, ...];
n=4: [1, 162,  14013,   894294,   56526498,  12817431900, ...];
n=5: [1, 486, 120771, 20555046, 2731197285, 334429044030, ...]; ...
in which the main diagonal equals this sequence shift left,
illustrating that a(n+1) = [x^n] A(x)^(2*3^n) for n >= 0.
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A=[1, 1]); for(i=1, n, A=concat(A, Vec(Ser(A)^(2*3^(#A-1)))[ #A])); A[n+1]}
    for(n=0,15,print1(a(n),", "))
    
  • PARI
    {a(n) = my(A=1+x); for(i=1, n, A = 1 + x*sum(m=0,#A, 2^m*log( subst(Ser(A),x,3^m*x +x*O(x^n)))^m/m!) ); polcoeff(A,n)}
    for(n=0,15,print1(a(n),", "))

Formula

G.f. A(x) = Sum_{n>=0} a(n)*x^n satisfies the following formulas.
(1) A(x) = 1 + x*Sum_{n>=0} 2^n*log( A(3^n*x) )^n / n!.
(2) a(n+1) = [x^n] A(x)^(2*3^n) for n >= 0, with a(0)=1.

A366227 O.g.f. A(x) satisfies: A(x) = 1 + x*Sum_{n>=0} 3^n * log( A(2^n*x) )^n / n!.

Original entry on oeis.org

1, 1, 6, 138, 8648, 1272948, 424058592, 334836466656, 728593565874816, 5632989888855720864, 184539760855097635059200, 25027477244647424010315231744, 13206715998089387470949589465286656, 26431031766456352400292737393044784872448, 199091399877503863934385670788355318673030504448
Offset: 0

Views

Author

Paul D. Hanna, Oct 17 2023

Keywords

Comments

In general, we have the following identity:
given A(x) = Sum_{n>=0} a(n)*x^n satisfies
A(x) = 1 + x*Sum_{n>=0} p^n * log( A(q^n*x) )^n / n!,
then a(n+1) = [x^n] A(x)^(p*q^n) for n >= 0, with a(0)=1,
for arbitrary fixed parameters p and q.
Here, p = 3 and q = 2.

Examples

			G.f.: A(x) = 1 + x + 6*x^2 + 138*x^3 + 8648*x^4 + 1272948*x^5 + 424058592*x^6 + 334836466656*x^7 + 728593565874816*x^8 + ...
where
A(x) = 1 + x*[1 + 3*log(A(2*x)) + 3^2*log(A(2^2*x))^2/2! + 3^3*log(A(2^2*x))^3/3! + ... + 3^n*log(A(2^n*x))^n/n! + ...].
RELATED SERIES.
log(A(x)) = x + 11*x^2/2 + 397*x^3/3 + 33991*x^4/4 + 6318201*x^5/5 + 2536406543*x^6/6 + 2340834765809*x^7/7 + ...
RELATED TABLE.
The table of coefficients of x^k in A(x)^(3*2^n) begins:
n=0: [1,   3,    21,     451,    26898,    3876222, ...];
n=1: [1,   6,    51,    1028,    56943,    7932774, ...];
n=2: [1,  12,   138,    2668,   128823,   16653720, ...];
n=3: [1,  24,   420,    8648,   340722,   37135560, ...];
n=4: [1,  48,  1416,   37456,  1272948,   97890096, ...];
n=5: [1,  96,  5136,  210848,  8146728,  424058592, ...];
n=6: [1, 192, 19488, 1407808, 83154768, 4578119616, 334836466656, ...]; ...
in which the main diagonal equals this sequence shift left,
illustrating that a(n+1) = [x^n] A(x)^(3*2^n) for n >= 0.
		

Crossrefs

Programs

  • PARI
    {a(n) = my(A=[1, 1]); for(i=1, n, A=concat(A, Vec(Ser(A)^(3*2^(#A-1)))[ #A])); A[n+1]}
    for(n=0, 15, print1(a(n), ", "))
    
  • PARI
    {a(n) = my(A=1+x); for(i=1, n, A = 1 + x*sum(m=0, #A, 3^m*log( subst(Ser(A), x, 2^m*x +x*O(x^n)))^m/m!) ); polcoeff(A, n)}
    for(n=0, 15, print1(a(n), ", "))

Formula

G.f. A(x) = Sum_{n>=0} a(n)*x^n satisfies the following formulas.
(1) A(x) = 1 + x*Sum_{n>=0} 3^n * log( A(2^n*x) )^n / n!.
(2) a(n+1) = [x^n] A(x)^(3*2^n) for n >= 0, with a(0)=1.
Showing 1-3 of 3 results.