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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A294221 Exponential transform of the square pyramidal numbers (A000330).

Original entry on oeis.org

1, 1, 6, 30, 192, 1471, 12637, 120723, 1267492, 14438913, 176961001, 2318180239, 32275104644, 475285152707, 7373223596299, 120078748361611, 2046720320727328, 36414341169682417, 674650306604656821, 12988470845576660407, 259348785562811740236, 5361803880323803698731, 114593610390850499426211
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 25 2017

Keywords

Examples

			E.g.f.: A(x) = 1 + x/1! + 6*x^2/2! + 30*x^3/3! + 192*x^4/4! + 1471*x^5/5! + 12637*x^6/6! + ...
		

Crossrefs

Programs

  • Mathematica
    Range[0, 22]! CoefficientList[Series[Exp[Exp[x] x (6 + 9 x + 2 x^2)/6], {x, 0, 22}], x]
    a[n_] := a[n] = Sum[a[n - k] Binomial[n - 1, k - 1] k (k + 1) (2 k + 1)/6, {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 22}]

Formula

E.g.f.: exp(exp(x)*x*(6 + 9*x + 2*x^2)/6).

A346749 E.g.f.: exp( (x * (1 + x) * exp(x) - sinh(x)) / 4 ).

Original entry on oeis.org

1, 0, 1, 2, 7, 26, 124, 628, 3565, 22096, 149176, 1080868, 8372543, 68957268, 601351748, 5528967282, 53416626441, 540682811424, 5718911631856, 63060992662328, 723382253378395, 8616075340134868, 106374847828850676, 1359171823319541070, 17946987240664242493
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 01 2021

Keywords

Comments

Exponential transform of A002620.

Crossrefs

Programs

  • Mathematica
    nmax = 24; CoefficientList[Series[Exp[(x (1 + x) Exp[x] - Sinh[x])/4], {x, 0, nmax}], x] Range[0, nmax]!
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n - 1, k - 1] Floor[k^2/4] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 24}]

Formula

a(0) = 1; a(n) = Sum_{k=1..n} binomial(n-1,k-1) * A002620(k) * a(n-k).
Previous Showing 11-12 of 12 results.