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.

A144692 G.f.: A(x) = x/Series_Reversion[x*G(x)] where A(x*G(x)) = G(x) = g.f. of A144691.

Original entry on oeis.org

1, 1, 1, 0, 17, 0, 408, 0, 69473, 0, 6018928, 0, 1363916728, 0, 219434809664, 0, 184186824259233, 0, 57411426894898072, 0, 38606038922780709192, 0, 16136153318586799828504, 0, 20401945614919621585224136, 0, 12864310266687158415460633528, 0
Offset: 0

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Author

Paul D. Hanna, Oct 10 2008

Keywords

Comments

Do the zeros continue to appear every other term?

Examples

			G.f.: A(x) = 1 + x + x^2 + 17*x^4 + 408*x^6 + 69473*x^8 + 6018928*x^10 +...
satisfies: A(x*G(x)) = G(x) = g.f. of A144691 where
G(x) = 1 + x + 2*x^2 + 4*x^3 + 26*x^4 + 106*x^5 + 816*x^6 + 4292*x^7 +...
		

Crossrefs

Cf. A144691.

Extensions

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

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

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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.

A144690 Limit of the coefficient of x^(2^m+n) in B(x)^(n+1) as m grows, where B(x) = Sum_{k>=0} x^(2^k).

Original entry on oeis.org

1, 2, 6, 16, 130, 636, 5712, 34336, 811458, 7151380, 113034746, 1049982792, 25276020640, 293841338896, 5712436923000, 68827002466176, 3739997267623490, 60752008945662372, 1718332635327516238, 26832922324005759560, 1099199814287516279394
Offset: 0

Views

Author

Paul D. Hanna, Oct 10 2008

Keywords

Comments

The g.f. of A144691(n) = a(n)/(n+1) appears to have an interesting functional interpretation.
For a fixed n, the sequence of [x^(2^m+n)] B(x)^(n+1), m=0,1,2,... seems to stabilize at m = n + A023416(n). [From Max Alekseyev, Dec 19 2011]

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),2^m+n)) }

Formula

a(n) = (n+1)*A144691(n).

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

A277041 Limit of the coefficient of x^(3^m + n) in B(x)^(n+1)/(n+1) as m grows, where B(x) = Sum_{k>=0} x^(3^k).

Original entry on oeis.org

1, 1, 1, 2, 5, 11, 51, 246, 897, 13526, 115631, 614681, 8739556, 89877217, 596072842
Offset: 0

Views

Author

Paul D. Hanna, Sep 25 2016

Keywords

Comments

The expansion of A(x/(1+x))/(1+x) appears to be a power series in x^3.

Examples

			G.f.: A(x) = 1 + x + x^2 + 2*x^3 + 5*x^4 + 11*x^5 + 51*x^6 + 246*x^7 + 897*x^8 + 13526*x^9 + 115631*x^10 + 614681*x^11 + 8739556*x^12 + 89877217*x^13 + 596072842*x^14 +...
RELATED SERIES.
A(x/G(x)) = G(x) = x/Series_Reversion[x*A(x)], where
G(x) = 1 + x + x^3 + 27*x^6 + 10666*x^9 + 6174792*x^12 +...+ A277042(n)*x^n +...
and G(x) appears to continue with powers of x^3 only.
The inverse binomial transform forms the g.f. of A277043:
A(x/(1+x))/(1+x) = 1 + x^3 + 30*x^6 + 10921*x^9 + 6308995*x^12 +...+ A277043(n)*x^n +...
which also appears to continue with powers of x^3 only.
		

Crossrefs

Programs

  • PARI
    { a(n) = my(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)/(n+1), 3^m+n) }
    for(n=0,10,print1(a(n),", "))

Formula

a(n) = A277040(n)/(n+1).
Equals the binomial transform of A277043.
Showing 1-4 of 4 results.