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.

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A289922 Coefficients of 1/([1+r] - [1+2r]x + [1+3r]x^2 - ...), where [ ] = floor and r = 19/21.

Original entry on oeis.org

1, 2, 1, 0, 0, 0, 0, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 0, 0, 0, 1, 2, -1, -5, -4, -1, 0, 0, 0, 0, 1, 1, -6, -15, -14, -6, -1, 0, 0, 0, 1, 0, -10, -21, -18, -7, -1, 0, 0, 0, 1, -1, -13, -20, -3, 18, 18, 7, 1, 0, 1, -2, -15, -13, 29
Offset: 0

Views

Author

Clark Kimberling, Jul 18 2017

Keywords

Crossrefs

Cf. A078140 (includes guide to related sequences), A289921, A289923.

Programs

  • Mathematica
    z = 2000; r = 19/21;
    CoefficientList[Series[1/Sum[Floor[1 + (k + 1)*r] (-x)^k, {k, 0, z}], {x, 0, z}],
      x];
  • PARI
    Vec((1 + x)^2*(1 - x + x^2)*(1 - x + x^2 - x^3 + x^4 - x^5 + x^6)*(1 + x - x^3 - x^4 + x^6 - x^8 - x^9 + x^11 + x^12) / (1 - x + x^2 - x^3 + x^4 - x^5 + x^6 - x^7 + x^8 - x^9 - x^11 + x^12 - x^13 + x^14 - x^15 + x^16 - x^17 + x^18 - x^19 + x^20 + x^21) + O(x^100)) \\ Colin Barker, Jul 21 2017

Formula

G.f.: 1/([1+r] - [1+2r]x + [1+3r]x^2 - ...), where [ ] = floor and r = 19/21.
G.f.: (1 + x)^2*(1 - x + x^2)*(1 - x + x^2 - x^3 + x^4 - x^5 + x^6)*(1 + x - x^3 - x^4 + x^6 - x^8 - x^9 + x^11 + x^12) / (1 - x + x^2 - x^3 + x^4 - x^5 + x^6 - x^7 + x^8 - x^9 - x^11 + x^12 - x^13 + x^14 - x^15 + x^16 - x^17 + x^18 - x^19 + x^20 + x^21). - Colin Barker, Jul 20 2017

A289923 Limiting sequence of coefficients of 1/([1+r] - [1+2r]x + [1+3r]x^2 - ...), where [ ] = floor and r approaches 19/21 from the left.

Original entry on oeis.org

1, 2, 1, 0, 0, 0, 0, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 0, 0, 0, 2, 7, 9, 5, 1, 0, 0, 0, 0, 0, 3, 12, 19, 15, 6, 1, 0, 0, 0, 0, 5, 22, 40, 39, 22, 7, 1, 0, 0, 0, 8, 39, 81, 94, 67, 30, 8, 1, 0, 0, 13, 69, 160, 214, 183, 104, 39, 9, 1, 0, 21, 121, 310, 468, 464
Offset: 0

Views

Author

Clark Kimberling, Jul 18 2017

Keywords

Comments

Conjecture: all the terms are nonnegative.

Crossrefs

Cf. A078140 (includes guide to related sequences), A289921, A289922.

Programs

  • Mathematica
    z = 2000; r = 19/21-10^(-9);
    CoefficientList[Series[1/Sum[Floor[1 + (k + 1)*r] (-x)^k, {k, 0, z}], {x, 0, z}],
      x];

Formula

G.f.: 1/([1+r] - [1+2r]x + [1+3r]x^2 - ...), where [ ] = floor and r = 19/21-10^(-9).
G.f.: (1 + x)^2*(1 - x + x^2)*(1 - x + x^2 - x^3 + x^4 - x^5 + x^6)*(1 + x - x^3 - x^4 + x^6 - x^8 - x^9 + x^11 + x^12) / (1 - x + x^2 - x^3 + x^4 - x^5 + x^6 - x^7 + x^8 - x^9 - x^11 + x^12 - x^13 + x^14 - x^15 + x^16 - x^17 + x^18 - x^19). - Colin Barker, Jul 20 2017
Showing 1-2 of 2 results.