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.

A328771 Minimal number of primorials (A002110) that add to A328768(n), where A328768 is the first primorial based variant of arithmetic derivative.

Original entry on oeis.org

0, 0, 1, 1, 2, 1, 2, 1, 2, 2, 5, 1, 4, 1, 4, 6, 2, 1, 3, 1, 4, 6, 6, 1, 6, 2, 5, 5, 10, 1, 6, 1, 6, 8, 7, 8, 6, 1, 6, 8, 6, 1, 5, 1, 8, 7, 8, 1, 6, 2, 9, 6, 10, 1, 8, 8, 8, 6, 9, 1, 10, 1, 4, 9, 8, 10, 13, 1, 8, 8, 14, 1, 10, 1, 5, 5, 10, 12, 10, 1, 6, 2, 7, 1, 8, 10, 6, 10, 14, 1, 5, 14, 8, 6, 8, 12, 6, 1, 9, 15, 8, 1, 16, 1, 14, 7
Offset: 0

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Author

Antti Karttunen, Oct 28 2019

Keywords

Crossrefs

Programs

  • PARI
    A002110(n) = prod(i=1,n,prime(i));
    A328768(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]*A002110(primepi(f[i,1])-1)/f[i, 1]));
    A276150(n) = { my(s=0, p=2, d); while(n, d = (n%p); s += d; n = (n-d)/p; p = nextprime(1+p)); (s); };
    A328771(n) = A276150(A328768(n));

Formula

a(n) = A276150(A328768(n)).