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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A207648 Expansion of e.g.f. Sum_{n>=0} 1/(n+1)! * Product_{k=1..n} ((1+x)^(n+k) - 1).

Original entry on oeis.org

1, 1, 5, 60, 1192, 34790, 1378380, 70445130, 4478636736, 344722776048, 31454679473280, 3345722335272240, 409180573835161920, 56883771843543627840, 8902319140111902785280, 1555438839901675382253600, 301239031844599064651635200, 64260075520580099615272097280
Offset: 0

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Author

Paul D. Hanna, Feb 19 2012

Keywords

Comments

Compare e.g.f. to: Sum_{n>=0} 1/(n+1)! * Product_{k=1..n} (n+k)*x, which is a g.f. of Catalan numbers (A000108).

Examples

			E.g.f.: A(x) = 1 + x + 5*x^2/2! + 60*x^3/3! + 1192*x^4/4! + 34790*x^5/5! +...
such that, by definition,
A(x) = 1 + ((1+x)^2-1)/2! + ((1+x)^3-1)*((1+x)^4-1)/3! + ((1+x)^4-1)*((1+x)^5-1)*((1+x)^6-1)/4! + ((1+x)^5-1)*((1+x)^6-1)*((1+x)^7-1)*((1+x)^8-1)/5! +...
		

Crossrefs

Cf. A207649.

Programs

  • PARI
    {a(n)=n!*polcoeff(sum(m=0,n,1/(m+1)!*prod(k=1,m,(1+x)^(m+k)-1 +x*O(x^n)) ),n)}
    for(n=0,25,print1(a(n),", "))

Formula

E.g.f.: Sum_{n>=0} 1/(n+1)! * Product_{k=1..n} ((1+x)^(n+k) - 1).
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