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.

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A157314 G.f.: A(x) = exp( Sum_{n>=1} A157313(n)*x^n/n ) = 1/Product_{n>=1} (1 - A157313(n-1)*x^n).

Original entry on oeis.org

1, 1, 2, 5, 16, 62, 298, 1700, 11448, 88622, 778532, 7636888, 82782697, 981775224, 12643542295, 175638751080, 2617558335383, 41650633309937, 704712768652527, 12632584581030449, 239150363847113653, 4767657035201958150
Offset: 0

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Author

Paul D. Hanna, Mar 10 2009

Keywords

Examples

			G.f.: A(x) = 1 + x + 2*x^2 + 5*x^3 + 16*x^4 + 62*x^5 + 298*x^6 +...
where the exponential:
A(x) = exp(x + 3*x^2/2 + 10*x^3/3 + 43*x^4/4 + 216*x^5/5 + 1326*x^6/6 +...)
and the product:
1/A(x) = (1 - x)(1 - x^2)(1 - 3*x^3)(1 - 10*x^4)(1 - 43*x^5)(1 - 216*x^6)*...
generate A(x) using the same coefficients (after initial term):
A157313=[1,1,3,10,43,216,1326,9283,74667,672085,6730098,74031079,...].
		

Crossrefs

A348661 a(1) = 1; a(n) = Sum_{d|n, d < n} d * a(d)^(n/d).

Original entry on oeis.org

1, 1, 1, 3, 1, 6, 1, 39, 4, 8, 1, 330, 1, 10, 9, 12495, 1, 1446, 1, 1620, 11, 14, 1, 1792050, 6, 16, 580, 10158, 1, 53002, 1, 2516534175, 15, 20, 13, 469241466, 1, 22, 17, 774558756, 1, 1696170, 1, 712914, 20160, 26, 1, 108457624531554, 8, 328588, 21, 6383964
Offset: 1

Views

Author

Ilya Gutkovskiy, Oct 28 2021

Keywords

Crossrefs

Cf. A006241, A008578 (positions of 1's), A157313, A165552, A196545, A281145.

Programs

  • Mathematica
    a[1] = 1; a[n_] := a[n] = Sum[If[d < n, d a[d]^(n/d), 0], {d, Divisors[n]}]; Table[a[n], {n, 1, 52}]

Formula

For n > 1, a(n) is the coefficient of x^n/n in expansion of -log(Product_{k=1..n-1} (1 - a(k)*x^k)).
Showing 1-2 of 2 results.