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.

A322209 L.g.f.: log( Product_{n>=1} 1/(1 - (2^n+1)*x^n) ).

Original entry on oeis.org

0, 3, 19, 54, 199, 408, 1612, 3090, 11023, 26487, 80994, 199686, 676540, 1700832, 5285096, 15197274, 45739039, 131368404, 401655943, 1172222958, 3549402474, 10533769146, 31617172980, 94336116834, 283990486780, 848323147233, 2546924693306, 7631598676410, 22903854049016, 68645946621360, 206035134959112, 617739968277066, 1853594327953471
Offset: 0

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Author

Paul D. Hanna, Dec 01 2018

Keywords

Examples

			L.g.f.: L(x) = 3*x + 19*x^2/2 + 54*x^3/3 + 199*x^4/4 + 408*x^5/5 + 1612*x^6/6 + 3090*x^7/7 + 11023*x^8/8 + 26487*x^9/9 + 80994*x^10/10 + 199686*x^11/11 + 676540*x^12/12 + ...
such that
exp( L(x) ) = 1 + 3*x + 14*x^2 + 51*x^3 + 195*x^4 + 663*x^5 + 2345*x^6 + 7707*x^7 + 25744*x^8 + 82980*x^9 + 267812*x^10 + 846150*x^11 + 2676163*x^12 + ... + A322199(n)*x^n + ...
also,
exp( L(x) ) = 1/( (1 - 3*x) * (1 - 5*x^2) * (1 - 9*x^3) * (1 - 17*x^4) * (1 - 33*x^5) * (1 - 65*x^6) * (1 - 129*x^7) * ... * (1 - (2^n+1)*x^n) * ... ).
		

Crossrefs

Programs

  • PARI
    {L = sum(n=1,41, -log(1 - (x^n + y^n) +O(x^41) +O(y^41)) );}
    {A322200(n,k) = polcoeff( (n+k)*polcoeff( L,n,x),k,y)}
    {a(n) = sum(k=0,n, A322200(n-k,k)*2^k )}
    for(n=0,40, print1( a(n),", ") )

Formula

a(n) = Sum_{k=0..n} A322200(n-k,k) * 2^k for n >= 0.