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.

A307488 G.f. A(x) satisfies: A(x) = 1 + Sum_{k>=1} mu(k)^2*x^k*A(x)^k/(1 - x^k*A(x)^k)^2, where mu() is the Möbius function (A008683).

Original entry on oeis.org

1, 1, 4, 14, 59, 257, 1185, 5609, 27259, 134911, 678252, 3452924, 17767047, 92248717, 482710548, 2543031236, 13477141627, 71800541745, 384320284096, 2065782153388, 11146084675905, 60346599617759, 327749929622743, 1785153353416807, 9748766110978057, 53367282644562541
Offset: 0

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Author

Ilya Gutkovskiy, Apr 10 2019

Keywords

Examples

			G.f.: A(x) = 1 + x + 4*x^2 + 14*x^3 + 59*x^4 + 257*x^5 + 1185*x^6 + 5609*x^7 + 27259*x^8 + 134911*x^9 + 678252*x^10 + ...
		

Crossrefs

Programs

  • Mathematica
    terms = 26; CoefficientList[1/x InverseSeries[Series[x/(1 + Sum[DirichletConvolve[i, MoebiusMu[i]^2, i, k] x^k, {k, 1, terms}]), {x, 0, terms}], x], x]
    terms = 26; A[] = 0; Do[A[x] = 1 + Sum[MoebiusMu[k]^2 x^k A[x]^k/(1 - x^k A[x]^k)^2, {k, 1, j}] + O[x]^j, {j, 1, terms}]; CoefficientList[A[x], x]
    terms = 26; A[] = 0; Do[A[x] = 1 + Sum[DirichletConvolve[i, MoebiusMu[i]^2, i, k] x^k A[x]^k, {k, 1, j}] + O[x]^j, {j, 1, terms}]; CoefficientList[A[x], x]

Formula

G.f. A(x) satisfies: A(x) = 1 + Sum_{k>=1} psi(k)*x^k*A(x)^k, where psi() is the Dedekind psi function (A001615).
G.f.: A(x) = (1/x)*Series_Reversion(x/(1 + Sum_{k>=1} psi(k)*x^k)).