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 1-5 of 5 results.

A009434 Expansion of e.g.f: log(1+x)/cosh(tanh(x)).

Original entry on oeis.org

0, 1, -1, -1, 0, 69, -225, -1653, 3976, 187401, -965385, -14516745, 61266744, 3032650893, -21187300953, -491788726653, 2947006495920, 166337505847057, -1463633608132017, -46261934493321105, 358635306874354320
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 30);
    [0] cat Coefficients(R!(Laplace( Log(1+x)/Cosh(Tanh(x)) ))); // G. C. Greubel, Sep 06 2023
    
  • Mathematica
    With[{nn=20},CoefficientList[Series[Log[1+x]/Cosh[Tanh[x]],{x,0,nn}], x] Range[0,nn]!] (* Harvey P. Dale, Jun 19 2013 *)
  • PARI
    my(x='x+O('x^30)); concat([0],Vec(serlaplace(log(1+x)/cosh(tanh(x))))) \\ Joerg Arndt, Sep 06 2023
  • SageMath
    def A009434_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( log(1+x)/cosh(tanh(x)) ).egf_to_ogf().list()
    A009434_list(40) # G. C. Greubel, Sep 06 2023
    

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997
Definition clarified and prior Mathematica program replaced by Harvey P. Dale, Jun 19 2013

A009436 Expansion of e.g.f. log(1+x)/exp(sin(x)).

Original entry on oeis.org

0, 1, -3, 8, -20, 59, -261, 1665, -12368, 99945, -888961, 8802045, -96423788, 1154791637, -14982150197, 209295667833, -3133083877248, 50039962416625, -849332973526881, 15266142375582901, -289679348425382572
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 30);
    [0] cat Coefficients(R!(Laplace( Log(1+x)*Exp(-Sin(x)) ))); // G. C. Greubel, Sep 08 2023
    
  • Mathematica
    With[{m=30}, CoefficientList[Series[Log[1+x]/E^Sin[x], {x,0,m}], x]*Range[0,m]!] (* Vaclav Kotesovec, Jan 23 2015 *)
  • SageMath
    def A009436_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( log(1+x)*exp(-sin(x)) ).egf_to_ogf().list()
    A009436_list(31) # G. C. Greubel, Sep 08 2023

Formula

a(n) ~ (n-1)! * (-1)^(n+1) * exp(sin(1)). - Vaclav Kotesovec, Jan 23 2015

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

A302610 Expansion of e.g.f. -log(1 - x)*arcsinh(x).

Original entry on oeis.org

0, 0, 2, 3, 4, 20, 158, 819, 3624, 33984, 427482, 3819915, 29665260, 404822340, 6948032310, 88407058635, 991515848400, 17715286764000, 383952670412850, 6349179054589875, 93532380775766100, 2063197602667372500, 53913667654307868750, 1098018631195048591875
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 10 2018

Keywords

Examples

			-log(1 - x)*arcsinh(x) = 2*x^2/2! + 3*x^3/3! + 4*x^4/4! + 20*x^5/5! + 158*x^6/6! + 819*x^7/7! + 3624*x^8/8! + ...
		

Crossrefs

Programs

  • Maple
    a:=series(-log(1-x)*arcsinh(x),x=0,24): seq(n!*coeff(a,x,n),n=0..23); # Paolo P. Lava, Mar 26 2019
  • Mathematica
    nmax = 23; CoefficientList[Series[-Log[1 - x] ArcSinh[x], {x, 0, nmax}], x] Range[0, nmax]!

Formula

E.g.f.: -log(1 - x)*log(x + sqrt(1 + x^2)).

A302611 Expansion of e.g.f. -log(1 - x)*arctanh(x).

Original entry on oeis.org

0, 0, 2, 3, 16, 50, 368, 1764, 16896, 109584, 1297152, 10628640, 149944320, 1486442880, 24349317120, 283465647360, 5287713177600, 70734282393600, 1480103564083200, 22376988058521600, 519000166327910400, 8752948036761600000, 222845873874075648000, 4148476779335454720000
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 10 2018

Keywords

Examples

			-log(1 - x)*arctanh(x) = 2*x^2/2! + 3*x^3/3! + 16*x^4/4! + 50*x^5/5! + 368*x^6/6! + 1764*x^7/7! + 16896*x^8/8! + ...
		

Crossrefs

Programs

  • Maple
    a:=series(-log(1-x)*arctanh(x),x=0,24): seq(n!*coeff(a,x,n),n=0..23); # Paolo P. Lava, Mar 26 2019
  • Mathematica
    nmax = 23; CoefficientList[Series[-Log[1 - x] ArcTanh[x], {x, 0, nmax}], x] Range[0, nmax]!
  • PARI
    x='x+O('x^99); concat([0, 0], Vec(serlaplace(log(1-x)*log((1-x)/(1+x))/2))) \\ Altug Alkan, Apr 10 2018

Formula

E.g.f.: log(1 - x)*log((1 - x)/(1 + x))/2.

A351883 Expansion of e.g.f. 1 / (1 - x)^sech(x).

Original entry on oeis.org

1, 1, 2, 3, 6, 35, 285, 2044, 13804, 108093, 1083405, 12281896, 143452386, 1763156031, 23845410407, 353626471808, 5579871336488, 92609430408361, 1627509065584185, 30379312334903408, 598533509334403470, 12366674489588950555, 267527916985316556019
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 23 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 22; CoefficientList[Series[1/(1 - x)^Sech[x], {x, 0, nmax}], x] Range[0, nmax]!
  • PARI
    my(x='x+O('x^30)); Vec(serlaplace(1/(1-x)^(1/cosh(x)))) \\ Michel Marcus, Feb 23 2022

Formula

a(0) = 1; a(n) = -Sum_{k=1..n} (-1)^k * binomial(n-1,k-1) * A009435(k) * a(n-k).
a(n) ~ n! / (Gamma(1/cosh(1)) * n^(1 - 1/cosh(1))). - Vaclav Kotesovec, Feb 24 2022
Showing 1-5 of 5 results.