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.

A260336 Numerators of Glaisher's J-numbers J_n.

Original entry on oeis.org

10, 34, 910, 415826, 3786350, 455594594, 226816276970, 16546152735874, 4616987879606830, 4799607558341375462, 674014218452089817870, 339274220304210587466434, 5429636257086663655134162970, 138634566648793083166951423714
Offset: 1

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Author

N. J. A. Sloane, Jul 29 2015

Keywords

Examples

			10/3, 34, 910, 415826/9, 3786350, 455594594, 226816276970/3, 16546152735874, 4616987879606830, ...
		

Crossrefs

Cf. A047789 (denominators).

Programs

  • Maple
    In := proc(n)
        1/(exp(x)+exp(-x)+1) ;
        coeftayl(%,x=0,2*n) ;
        %*(2*n)!*(-1)^n*3/2 ;
    end proc:
    Jn := proc(n)
        (2^(2*n+1)+2)*In(n) ;
    end proc:
    A260336 := proc(n)
        numer(Jn(n)) ;
    end proc: # R. J. Mathar, Aug 02 2015
  • Mathematica
    GI[n_] := SeriesCoefficient[1/(Exp[x]+Exp[-x]+1), {x, 0, 2n}]*(2n)!*(-1)^n*3/2;
    GJ[n_] := (2^(2n+1)+2)*GI[n];
    a[n_] := Numerator[GJ[n]];
    Table[a[n], {n, 1, 14}] (* Jean-François Alcover, Apr 15 2023, after R. J. Mathar *)