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.

A001488 Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^10 in powers of x.

Original entry on oeis.org

1, -10, 45, -120, 200, -162, -160, 810, -1530, 1730, -749, -1630, 4755, -7070, 6700, -2450, -5295, 14070, -20010, 19350, -10157, -6290, 25515, -40660, 44940, -34268, 9180, 24510, -57195, 78060, -79087, 56610, -13935, -39600, 89805, -121638, 125405
Offset: 10

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References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Magma
    m:=102;
    R:=PowerSeriesRing(Integers(), m);
    Coefficients(R!( ((&*[1-(-x)^j: j in [1..m+2]]) -1)^10 )); // G. C. Greubel, Sep 04 2023
    
  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(add([-d, d, -2*d, d]
          [1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
        end:
    b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0, g(n)),
          (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    a:= n-> b(n, 10):
    seq(a(n), n=10..46);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax=46; CoefficientList[Series[(Product[(1-(-x)^j), {j,nmax}] -1)^10, {x,0,nmax}], x]//Drop[#,10] & (* Ilya Gutkovskiy, Feb 07 2021 *)
    Drop[CoefficientList[Series[(QPochhammer[-x] -1)^10, {x,0,102}], x],10] (* G. C. Greubel, Sep 04 2023 *)
  • PARI
    my(N=55,x='x+O('x^N)); Vec((eta(-x)-1)^10) \\ Joerg Arndt, Sep 05 2023
  • SageMath
    from sage.modular.etaproducts import qexp_eta
    m=100; k=10;
    def f(k,x): return (-1 + qexp_eta(QQ[['q']], m+2).subs(q=-x) )^k
    def A001488_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(k,x) ).list()
    a=A001488_list(m); a[k:] # G. C. Greubel, Sep 04 2023
    

Formula

a(n) = [x^n]( QPochhammer(-x) - 1 )^10. - G. C. Greubel, Sep 04 2023

Extensions

Definition and offset edited by Ilya Gutkovskiy, Feb 07 2021