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.

A300236 Möbius transform of A032742 (the largest proper divisor of n).

Original entry on oeis.org

1, 0, 0, 1, 0, 2, 0, 2, 2, 4, 0, 2, 0, 6, 4, 4, 0, 4, 0, 4, 6, 10, 0, 4, 4, 12, 6, 6, 0, 4, 0, 8, 10, 16, 6, 6, 0, 18, 12, 8, 0, 6, 0, 10, 8, 22, 0, 8, 6, 16, 16, 12, 0, 12, 10, 12, 18, 28, 0, 8, 0, 30, 12, 16, 12, 10, 0, 16, 22, 18, 0, 12, 0, 36, 16, 18, 10, 12, 0, 16, 18, 40, 0, 12, 16, 42, 28, 20, 0, 16, 12, 22, 30, 46, 18, 16, 0, 36
Offset: 1

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Author

Antti Karttunen, Mar 10 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[DivisorSum[n, # MoebiusMu[n/#]/FactorInteger[#][[1, 1]] &], {n, 98}] (* Michael De Vlieger, Mar 10 2018 *)
  • PARI
    A032742(n) = if(1==n,n,n/vecmin(factor(n)[,1]));
    A300236(n) = sumdiv(n,d,moebius(n/d)*A032742(d));

Formula

a(n) = Sum_{d|n} A008683(n/d)*A032742(d).