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.

A187111 Series inversion of A007296.

Original entry on oeis.org

1, 2, -1, 3, -11, 44, -187, 827, -3751, 17313, -81004, 383390, -1833029, 8843224, -43007753, 210670655, -1038597645, 5149654796, -25664518105, 128493771585, -645988558986, 3259776393676, -16505191207192, 83828620957326, -426961815072785
Offset: 0

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Author

Vladimir Kruchinin, Mar 05 2011

Keywords

Comments

The generating function A007296(x) = x - 2*x^2 + 5*x^3 - 15*x^4 + ... is a reversion of A008578(x) = x + 2*x^2 + 3*x^3 + ... with A007296(A008578(x))=x. The ordinary generating function A(x) = x/(x - 2*x + 5*x^2 - 15*x^3 + ...) = 1 + 2*x - x^2 + ... of this sequence here obeys A008578(x)=x*A(A008578(x)).

Programs

  • Maple
    read("transforms") ;
    Lp := [ 0,1,seq(ithprime(i),i=1..25) ] ;
    a007296 := REVERT(Lp) ;
    a007296x := add( op(i,a007296)*x^i,i=1..nops(a007296)) ;
    a187111x := taylor(x/a007296x ,x=0,nops(a007296)+1);
    for n from 0 to nops(a007296)-1 do printf("%d,",coeftayl(a187111x,x=0,n)) ; end do; # R. J. Mathar, Mar 29 2011

A334263 E.g.f. A(x) satisfies: A(x) = x - Sum_{k>=2} prime(k-1) * A(x)^k / k!.

Original entry on oeis.org

1, -2, 9, -65, 653, -8432, 133190, -2488589, 53690330, -1313508417, 35929413073, -1086587503799, 35998774583176, -1296581783771904, 50442455219483951, -2108020240791081088, 94179374365406507609, -4479409651990684350045, 225977974437623955594777
Offset: 1

Views

Author

Ilya Gutkovskiy, Apr 20 2020

Keywords

Comments

Exponential reversion of A008578 (1 together with primes).

Crossrefs

Programs

  • Mathematica
    nmax = 19; CoefficientList[InverseSeries[Series[x + Sum[Prime[k - 1] x^k/k!, {k, 2, nmax}], {x, 0, nmax}], x], x] Range[0, nmax]! // Rest

Formula

a(n) ~ -(-1)^n * n^(n-1) / (sqrt(t) * r^(n - 1/2) * exp(n)), where t = Sum_{k>=0} prime(k+1) * s^k / k! = 0.7444466039931411886049681349033665583265654464..., s = -0.835708320094278846648094879804371313211261254223... is the root of the equation Sum_{k>=1} prime(k) * s^k / k! = -1 and r = -s - Sum_{k>=2} prime(k-1) * s^k / k! = 0.34673082109620141270389189466020238662524394743... - Vaclav Kotesovec, Apr 21 2020

A291533 Expansion of the series reversion of g.f. for the nonprime numbers (A018252).

Original entry on oeis.org

1, -4, 26, -208, 1859, -17790, 178308, -1847882, 19640154, -212911066, 2345049018, -26168243862, 295214515662, -3361428239216, 38580429168968, -445874925644701, 5184317812361117, -60603410700370525, 711826341810784570, -8396670336877539127, 99428914632341468974
Offset: 1

Views

Author

Ilya Gutkovskiy, Aug 25 2017

Keywords

Crossrefs

Formula

G.f. A(x) satisfies: A(x) + 4*A(x)^2 + 6*A(x)^3 + 8*A(x)^4 + 9*A(x)^5 + 10*A(x)^6 + 12*A(x)^7 + ... = x.

A366011 G.f. A(x) satisfies: A(x) = x - Sum_{k>=2} prime(k) * A(x)^k.

Original entry on oeis.org

1, -3, 13, -67, 379, -2267, 14065, -89515, 580379, -3815731, 25356051, -169898467, 1145825123, -7767073859, 52858784539, -360823702851, 2468606626813, -16915880702563, 116028193869805, -796200367684945, 5463239318586601, -37465765826805457, 256664142145450777, -1755608165010431139
Offset: 1

Views

Author

Ilya Gutkovskiy, Sep 25 2023

Keywords

Comments

Reversion of g.f. for odd prime numbers together with 1.

Crossrefs

Programs

  • Mathematica
    nmax = 24; A[] = 0; Do[A[x] = x - Sum[Prime[k] A[x]^k, {k, 2, nmax}] + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x] // Rest
    nmax = 24; CoefficientList[InverseSeries[Series[x + Sum[Prime[k] x^k, {k, 2, nmax}], {x, 0, nmax}], x], x] // Rest
Showing 1-4 of 4 results.