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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A115659 Permutation of natural numbers generated by 2-rowed array shown below.

Original entry on oeis.org

0, 3, 1, 4, 2, 7, 5, 8, 6, 11, 9, 12, 10, 15, 13, 16, 14, 19, 17, 20, 18, 23, 21, 24, 22, 27, 25, 28, 26, 31, 29, 32, 30, 35, 33, 36, 34, 39, 37, 40, 38, 43, 41, 44, 42, 47, 45, 48, 46, 51, 49, 52, 50, 55, 53, 56, 54, 59, 57, 60, 58, 63, 61, 64, 62
Offset: 1

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Author

Giovanni Teofilatto, Mar 18 2006

Keywords

Comments

0 3 4 7 8 11 12 15 ...: integers congruent to 0 or 3 mod 4.
1 2 5 6 9 10 13 14 ...: integers congruent to 1 or 2 mod 4.
Essentially the same as A067060. - Hugo Pfoertner, Jun 16 2024

References

  • M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988.
  • Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta, UTET, CittaStudiEdizioni, Milano 1997.

Crossrefs

Programs

  • Magma
    I:=[0, 3, 1, 4, 2, 7]; [n le 6 select I[n] else Self(n-1)+Self(n-4)-Self(n-5): n in [1..70]]; // Vincenzo Librandi, Dec 02 2016
  • Mathematica
    Join[{0}, LinearRecurrence[{1, 0, 0, 1, -1}, {3, 1, 4, 2, 7}, 70]] (* Vincenzo Librandi, Dec 02 2016 *)

Formula

For n>0, a(n+4k) = a(n) + 4k, with k>=0.
G.f.: x^2*(3 - 2*x + 3*x^2 - 2*x^3 + 2*x^4)/(1 - x - x^4 + x^5). - Philippe Deléham, Dec 02 2016

Extensions

Entries corrected by R. J. Mathar, Oct 25 2011
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