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 1-2 of 2 results.

A317201 Reverse of A317199(n).

Original entry on oeis.org

21, 312, 1213, 213121, 3121121312
Offset: 1

Views

Author

N. J. A. Sloane, Aug 05 2018

Keywords

Comments

With a different offset, this is F_n in Bo Tan et al., pp. 1706ff.

Links

Crossrefs

Cf. A317199.

A317200 Expansion of g.f. -x*(2*x^3+2*x^2+x-2)/(x^4-2*x+1).

Original entry on oeis.org

0, 2, 3, 4, 6, 10, 17, 30, 54, 98, 179, 328, 602, 1106, 2033, 3738, 6874, 12642, 23251, 42764, 78654, 144666, 266081, 489398, 900142, 1655618, 3045155, 5600912, 10301682, 18947746, 34850337, 64099762, 117897842, 216847938, 398845539, 733591316, 1349284790, 2481721642
Offset: 1

Views

Author

N. J. A. Sloane, Aug 05 2018

Keywords

Comments

a(n) = length of A317199(n).

Links

Crossrefs

Cf. A000073, A317199.

Programs

  • Mathematica
    CoefficientList[Series[-x(2x^3+2x^2+x-2)/(x^4-2x+1),{x,0,40}],x] (* Harvey P. Dale, Aug 31 2020 *)
  • PARI
    my(N=40); Vec(x*(2 - x - 2*x^2 - 2*x^3)/((1 - x)*(1 - x - x^2 - x^3)) + O(x^N), -N) \\ Andrew Howroyd, Oct 24 2023

Formula

Bo Tan et al. express a(n) in terms of the tribonacci numbers A000073.

Extensions

Zero prepended by Harvey P. Dale, Aug 31 2020
a(36)-a(38) from Stefano Spezia, Oct 24 2023
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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