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.

Showing 1-4 of 4 results.

A144691 Limit of the coefficient of x^(2^m+n) in B(x)^(n+1)/(n+1) as m grows, where B(x) = Sum_{k>=0} x^(2^k).

Original entry on oeis.org

1, 1, 2, 4, 26, 106, 816, 4292, 90162, 715138, 10275886, 87498566, 1944309280, 20988667064, 380829128200, 4301687654136, 219999839271970, 3375111608092354, 90438559754079802, 1341646116200287978, 52342848299405537114, 921821277222438350170
Offset: 0

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Author

Paul D. Hanna, Oct 10 2008

Keywords

Examples

			G.f.: A(x) = 1 + x + 2*x^2 + 4*x^3 + 26*x^4 + 106*x^5 + 816*x^6 +...
A(x/G(x)) = G(x) = x/Series_Reversion[x*A(x)], where
G(x) = 1 + x + x^2 + 17*x^4 + 408*x^6 + 69473*x^8 + 6018928*x^10 +...
and G(x) appears to continue with only even powers of x (cf. A144692).
The inverse binomial transform forms the g.f. of A202582:
A(x/(1+x))/(1+x) = 1 + x^2 + 19*x^4 + 515*x^6 + 74383*x^8 + 6816465*x^10 +...+ A202582(n)*x^n +...
		

Crossrefs

Programs

  • PARI
    { a(n) = local(m=n+log(n+.5)\log(2), B=sum(k=0,m,x^(2^k))); if(n<0, 0, polcoeff((B+O(x^(2^m+n+1)))^(n+1)/(n+1),2^m+n)) }

Formula

a(n) = A144690(n)/(n+1).
G.f. A(x) satisfies: A(x/(1+x))/(1+x) is an even function; i.e., the inverse binomial transform yields A202582.

Extensions

a(14), a(15) corrected and a(16)-a(23) added by Max Alekseyev, May 03 2011
a(24)-a(27) in b-file from Max Alekseyev, Dec 19 2011

A166488 Number of transpose-isomorphism classes of SOLSSOMs of order n.

Original entry on oeis.org

31, 749, 0, 1210622, 1248307242, 640121719688, 0
Offset: 4

Views

Author

Martin P Kidd, Oct 21 2009

Keywords

Comments

A SOLSSOM is a self-orthogonal Latin square with a symmetric orthogonal mate. Two SOLSSOMs (L,S) and (L',S') are transpose-isomorphic if a permutation applied to the rows, columns and symbols of L and S maps (L,S) to (L',S') or (L'',S') (where L'' is the transpose of L').

References

  • A.P. Burger, M.P. Kidd and J.H. van Vuuren, Enumeration of self-orthogonal Latin squares with symmetric orthogonal mates, Submitted to LitNet Akademies (Natuurwetenskappe)

Crossrefs

Extensions

Class name and definition corrected by Martin P Kidd, Nov 01 2010

A277040 Limit of the coefficient of x^(3^m + n) in B(x)^(n+1) as m grows, where B(x) = Sum_{k>=0} x^(3^k).

Original entry on oeis.org

1, 2, 3, 8, 25, 66, 357, 1968, 8073, 135260, 1271941, 7376172, 113614228, 1258281038, 8941092630
Offset: 0

Views

Author

Paul D. Hanna, Sep 25 2016

Keywords

Comments

The g.f. of A277041(n) = a(n)/(n+1) appears to have an interesting functional interpretation.

Crossrefs

Programs

  • PARI
    { a(n) = local(m=n + ceil(log(n+3)/log(3)), B=sum(k=0, m, x^(3^k))); polcoeff((B+O(x^(3^m+n+1)))^(n+1), 3^m+n) }
    for(n=0,15,print1(a(n),", "))

Formula

a(n) = (n+1)*A277041(n).

A202582 Inverse binomial transform of A144691.

Original entry on oeis.org

1, 0, 1, 0, 19, 0, 515, 0, 74383, 0, 6816465, 0, 1457117673, 0, 241183200687, 0, 188350353304919, 0, 60855583632497865, 0, 39858196864723826583, 0, 17024263169695049621551, 0, 20817292362271689177123509, 0, 13408255577123563666760376685, 0
Offset: 0

Views

Author

Paul D. Hanna, Dec 21 2011

Keywords

Comments

A144691 is defined by: A144691(n) = limit of the coefficient of x^(2^m+n) in B(x)^(n+1)/(n+1) as m grows, where B(x) = Sum_{k>=0} x^(2^k).

Examples

			G.f.: A(x) = 1 + x^2 + 19*x^4 + 515*x^6 + 74383*x^8 + 6816465*x^10 +...
where
x/Series_Reversion(x*A(x)) = 1 + x^2 + 17*x^4 + 408*x^6 + 69473*x^8 + 6018928*x^10 +...+ A144692(n)*x^n +...
The g.f. G(x) of A144692 begins:
G(x) = 1 + x + x^2 + 17*x^4 + 408*x^6 + 69473*x^8 + 6018928*x^10 +...
where G(x) satisfies: A(x) = G(x*A(x))/(1+x) and G(x) = A(x/(G(x)-x)) + x.
		

Crossrefs

Formula

G.f. A(x) satisfies: x/Series_Reversion(x*A(x)) = G(x) - x, so that G(x*A(x)) = (1+x)*A(x) and A(x/(G(x) - x)) = G(x) - x, where G(x) is the g.f. of A144692.
Showing 1-4 of 4 results.