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.

A318886 The sum of absolute values of the coefficients in the n-th cyclotomic polynomial minus the largest prime factor of n; a(1)=1 by convention.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 4, 0, 10, 0, 0, 0, 4, 0, 0, 2, 0, 0, 2, 0, 0, 0, 0, 0, 6, 0, 0, 0, 6, 0, 6, 0, 0, 2, 0, 0, 2, 0, 18, 4, 0, 0, 8, 10, 0, 0, 0, 0, 2, 0, 20, 4, 0, 0, 0, 0, 0, 2, 24, 0, 10, 0, 0, 2, 10, 0, 10, 0, 12, 0, 0, 0, 4, 0, 0, 6, 0, 0, 28
Offset: 1

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Author

Antti Karttunen, Sep 10 2018

Keywords

Comments

See comments in A070536.

Crossrefs

Differs from A070536 for the first time at n=105, where a(105) = 28, while A070536(105) = 26.

Programs

  • Mathematica
    Array[Total@ Abs@ CoefficientList[Cyclotomic[#, x], x] - FactorInteger[#][[-1, 1]] &, 105] (* Michael De Vlieger, Sep 10 2018 *)
  • PARI
    A006530(n) = if(n>1, vecmax(factor(n)[, 1]), 1); \\ From A006530.
    A318884(n) = vecsum(apply(abs,Vec(polcyclo(n))));
    A318886(n) = (A318884(n) - A006530(n));