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.

A170925 G.f.: eta(q)*eta(q^2)*eta(q^4)*eta(q^8)*eta(q^16)*eta(q^32)*..., where eta(q) = Product((1-q^m), m=1..oo).

Original entry on oeis.org

1, -1, -2, 1, -1, 3, 3, -1, -2, -2, 4, -4, -1, -3, -3, 2, 1, 9, -1, 6, 7, -8, -10, 1, -1, 0, -2, 0, 2, -1, 4, -4, -1, -5, 14, -15, -7, 9, 11, 7, 0, 3, -14, 17, -7, 18, 4, -6, -7, -25, -12, -5, -13, -3, 9, -14, 25, 10, -2, 8, 17, 1, 2, 13, 4, 0, -4, 7, 13, -27, -42, 11, 5, 5, 10, -24, 3, -21, -4, 0, -32, 27, 29, -1, -4, 43, 26, -7, -41, -9, 27, -11
Offset: 0

Views

Author

N. J. A. Sloane and Gary W. Adamson, Feb 18 2010

Keywords

Comments

eta(q) = A(q)/A(q^2), where A(q) is the g.f. for this sequence (cf. A010815).

Crossrefs

Programs

  • Mathematica
    nmax = 100; CoefficientList[Series[Product[QPochhammer[x^(2^k)], {k, 0, Log[nmax]/Log[2]}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Sep 23 2019 *)
  • Ruby
    def s(k, n)
      s = 0
      (1..n).each{|i| s += i if n % i == 0 && i % k == 0}
      s
    end
    def A(ary, n)
      a_ary = [1]
      a = [0] + (1..n).map{|i| ary.inject(0){|s, j| s + j[1] * s(j[0], i)}}
      (1..n).each{|i| a_ary << (1..i).inject(0){|s, j| s - a[j] * a_ary[-j]} / i}
      a_ary
    end
    def A170925(n)
      A((0..Math.log(n, 2)).map{|i| [2 ** i, 1]}, n)
    end
    p A170925(100) # Seiichi Manyama, Sep 23 2019

A143374 G.f.: eta(q)*eta(q^3)*eta(q^9)*eta(q^27)*eta(q^81)*eta(q^243)*..., where eta(q) = Product((1-q^m), m=1..oo).

Original entry on oeis.org

1, -1, -1, -1, 1, 2, -1, 2, 0, -1, 0, 0, 0, -2, -2, 2, -3, -1, 1, 2, 3, 4, 1, -3, 0, -2, 3, -4, 2, 0, -1, -1, -2, -1, 0, -2, -2, 2, 2, -1, 0, 5, -1, 5, 0, 2, -3, -3, -3, 1, 3, 2, 2, -2, 4, -6, -4, 2, -2, -1, 2, -6, 0, 8, -4, -3, 2, 5, 1, -6, 3, 6, -1, 1, -4, -10, 1, 2, -1, 2, -5, -2, 6, 13, 4, 1, -1, 2, 1, 4, -4, -1
Offset: 0

Views

Author

N. J. A. Sloane and Gary W. Adamson, Feb 18 2010, Aug 14 2011

Keywords

Comments

eta(q) = A(q)/A(q^3), where A(q) is the g.f. for this sequence (cf. A010815).

Crossrefs

A160832 Expansion of eta(q)*eta(q^2)*eta(q^4), where eta(q) = Product((1-q^m), m=1..oo).

Original entry on oeis.org

1, -1, -2, 1, -1, 3, 3, -1, -1, -3, 2, -3, -2, 0, 0, 1, 2, 4, -3, 5, 3, -2, -4, 0, -2, -1, 1, -2, 2, -6, -3, -1, 3, 4, 5, -3, 2, 2, 3, 4, -7, 1, 4, -1, -3, 1, -4, 0, -4, 1, -2, 1, -2, -3, 1, -5, 0, 4, 1, 3, 5, 1, 4, -1, 7, -5, -2, 0, 0, -1, -2, 6, 8, -5, -5, -4, -3, 0, -1, 0, -6, -1, -3, 3, -3, 6, -2, -6, 6, 1, -4, 6, 0, 5, 6, 7, -5, -4, 4, -5, 2, 4, 6, -4, -3
Offset: 0

Views

Author

N. J. A. Sloane and Gary W. Adamson, Feb 18 2010

Keywords

Crossrefs

Programs

  • Mathematica
    eta[q_]:= q^(1/24)*QPochhammer[q]; CoefficientList[Series[q^(-7/24)* eta[q]*eta[q^2]*eta[q^4], {q, 0, 100}], q] (* G. C. Greubel, Apr 30 2018 *)
  • PARI
    q='q+O('q^50); Vec(eta(q)*eta(q^2)*eta(q^4)) \\ G. C. Greubel, Apr 30 2018

A194087 G.f.: eta(q)*eta(q^4)*eta(q^16)*eta(q^64)*eta(q^256)*eta(q^1024)*..., where eta(q) = Product_{m=1..oo} (1 - q^m).

Original entry on oeis.org

1, -1, -1, 0, -1, 2, 1, 1, -1, 0, 1, -1, -1, -1, 0, -2, 0, 1, 1, 1, 3, -3, -1, 0, 1, 1, -1, 2, 2, 0, -3, 2, -3, 2, 0, -2, -1, -1, -1, -1, -1, -1, 0, 0, 1, 2, 4, 2, 0, 0, 3, 1, -2, 0, 1, -5, 2, 0, -1, -2, -3, 1, 3, 0, 0, -3, 0, -1, 0, -1, -4, 2, 4, -1, -2, 3, 1, 1, -1, 3, 1, 0, -5, 0, -3, 8, 2, 3, -1, -3, 0, -3, -1, 0, 1
Offset: 0

Views

Author

N. J. A. Sloane and Gary W. Adamson, Feb 18 2010, Aug 14 2011

Keywords

Comments

eta(q) = A(q)/A(q^4), where A(q) is the g.f. for this sequence (cf. A010815).

Crossrefs

Showing 1-4 of 4 results.