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.

A255825 A self-generating sequence: a(n) = n for n < 5; a(5n) = a(n); if every 5th term (a(5), a(10), a(15),...) is deleted, this gives back the original sequence.

Original entry on oeis.org

1, 2, 3, 4, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 3, 1, 2, 3, 1, 4, 2, 3, 1, 4, 1, 2, 3, 1, 4, 1, 1, 2, 3, 1, 1, 4, 1, 1, 2, 1, 3, 1, 1, 4, 1, 1, 1, 2, 1, 2, 3, 1, 1, 4, 1, 1, 1, 1, 2, 2, 1, 2, 3, 1, 1, 1, 4, 1, 1, 2, 1, 1, 2, 2, 3, 1, 2, 3, 1, 1, 1, 1, 4, 1, 2, 1, 2, 1, 1, 3, 2, 2, 3, 1, 1, 2, 3, 1, 1, 4
Offset: 1

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Author

M. F. Hasler, Mar 07 2015

Keywords

Comments

This is the m=5 analog of the m=10 variant A126616. Sequence A117943 is the m=3 analog with all terms decreased by 1.

Crossrefs

Programs

  • PARI
    a(n, m=5)=while(n>=m, if(n%m, n-=n\m, n\=m)); n \\ M. F. Hasler, Mar 07 2015

Formula

a(n) = a(n/5) if n==0 (mod 5); a(n) = a(n - floor(n/5)) otherwise.