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.

A296728 Expansion of e.g.f. arcsin(x*cos(x)) (odd powers only).

Original entry on oeis.org

1, -2, -16, 8, 12672, 571264, -44351360, -12355211520, -452681248768, 478190483394560, 132554796040912896, -18854516962334277632, -27186884683859043123200, -5502410397289951851773952, 6273206188133923322747420672, 5389680791235134726930445369344
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 19 2017

Keywords

Examples

			arcsin(x*cos(x)) = x/1! - 2*x^3/3! - 16*x^5/5! + 8*x^7/7! + 12672*x^9/9! + ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 16; Table[(CoefficientList[Series[ArcSin[x Cos[x]], {x, 0, 2 nmax + 1}], x] Range[0, 2 nmax + 1]!)[[n]], {n, 2, 2 nmax, 2}]
  • PARI
    first(n) = x='x+O('x^(2*n)); vecextract(Vec(serlaplace(asin(x*cos(x)))), (4^n - 1)/3) \\ Iain Fox, Dec 19 2017

Formula

a(n) = (2*n+1)! * [x^(2*n+1)] arcsin(x*cos(x)).

A296729 Expansion of e.g.f. arcsin(x*cosh(x)) (odd powers only).

Original entry on oeis.org

1, 4, 44, 1912, 156816, 21506816, 4420845376, 1271132964480, 487161448339712, 239980527068474368, 147742478026391141376, 111153314734461183924224, 100339775128577885016985600, 107037870347952811373977239552, 133204585741561810426003651444736
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 19 2017

Keywords

Examples

			arcsin(x*cosh(x)) = x/1! + 4*x^3/3! + 44*x^5/5! + 1912*x^7/7! + 156816*x^9/9! + ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 15; Table[(CoefficientList[Series[ArcSin[x Cosh[x]], {x, 0, 2 nmax + 1}], x] Range[0, 2 nmax + 1]!)[[n]], {n, 2, 2 nmax, 2}]
  • PARI
    first(n) = x='x+O('x^(2*n)); vecextract(Vec(serlaplace(asin(x*cosh(x)))), (4^n - 1)/3) \\ Iain Fox, Dec 19 2017

Formula

a(n) = (2*n+1)! * [x^(2*n+1)] arcsin(x*cosh(x)).

A101922 Numerators of expansion of e.g.f. 2^(-1/2) * arcsinh(cos(x)), even powers only.

Original entry on oeis.org

-1, -1, 11, 491, 11159, -460681, -103577629, -8160790429, 624333860399, 386787409545839, 68810049201689531, -6999828208693648549, -9872674440874152431161, -3255253386897615662908441, 346248578699462435167833491, 1072454627614122049417452882131
Offset: 1

Views

Author

Ralf Stephan, Dec 27 2004

Keywords

Comments

With sign pattern +--+--: numerators of expansion of 2^(-1/2) * arcsinh(cosh(x)).
Odd coefficients are zero, denominators are 2^n.

Crossrefs

Programs

  • Mathematica
    Table[Numerator[(2n)!SeriesCoefficient[ArcSinh[Cos[x]]/Sqrt[2],{x,0,2n}]],{n,14}] (* Stefano Spezia, Aug 29 2022 *)
  • PARI
    lista(nn) = my(x='x + O('x^(nn+1)), p=serlaplace(asinh(cos(x))/sqrt(2))); vector(nn\2, k, round(polcoef(p, 2*k)*2^k)); \\ Michel Marcus, Sep 11 2022

Formula

arcsinh(cos(x)) = log(sqrt(2)+1) + 1/sqrt(2) * (-(1/2)*x^2/2! - (1/4)*x^4/4! + (11/8)*x^6/6! + (491/16)*x^8/8! + ...).
arccosh(cos(x)) = Pi/2 - log(sqrt(2)+1) + 1/sqrt(2) * ((1/2)*x^2/2! + (1/4)*x^4/4! - (11/8)*x^6/6! - (491/16)*x^8/8! - ...).
a(n) = - A263246(n). - Michel Marcus, Sep 11 2022

Extensions

More terms from Michel Marcus, Sep 11 2022

A101924 Numerators of expansion of e.g.f. 2^(-1/2) * arccsch(cos(x)), even powers only.

Original entry on oeis.org

1, 7, 109, 3163, 166201, 14952367, 2002052389, 353291166403, 77829008955121, 21170264082173527, 7106489649576530269, 2913186117837522604843, 1426879448953133350342441, 816516326741659045770111487, 537701607855913139967684905749, 404270165862091267387117902574483
Offset: 1

Views

Author

Ralf Stephan, Dec 27 2004

Keywords

Comments

Odd coefficients are zero, denominators are 2^n.

Crossrefs

Programs

  • Mathematica
    Table[Numerator[(2n)!SeriesCoefficient[ArcCsch[Cos[x]]/Sqrt[2], {x,0,2n}]],{n,14}] (* Stefano Spezia, Aug 29 2022 *)
  • PARI
    arccsch(x) = log((1+sqrt(x^2+1))/x);
    lista(nn) = localprec(4*nn); my(x='x+O('x^(nn+1)), v=Vec((serlaplace(arccsch(cos(x))))/quadgen(8))); apply(round, vector(#v\2-1, k, v[2*k+1]*2^k)); \\ Michel Marcus, Sep 21 2022

Formula

arccsch(cos(x)) = log(sqrt(2)+1) + (1/sqrt(2)) * ((1/2)*x^2/2! + (7/4)*x^4/4! + (109/8)*x^6/6! + (3163/16)*x^8/8! + ...).
arcsech(cos(x)) = Pi/2 - log(sqrt(2)+1) - (1/sqrt(2)) * (-(1/2)*x^2/2! + (7/4)*x^4/4! + (109/8)*x^6/6! + (3163/16)*x^8/8! + ...). [warning: this formula appears to be incorrect since arcsech(cos(0)) = 0; - Michel Marcus, Sep 23 2022]

Extensions

More terms from Michel Marcus, Sep 20 2022
Showing 1-4 of 4 results.