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.

A370120 a(n) = A276085(A370117(n)), where A370117(n) is the denominator of n/A276086(A003415(n)), A003415 is the arithmetic derivative, A276086 is the primorial base exp-function, and A276085 is its inverse, the primorial base log-function.

Original entry on oeis.org

0, 0, 0, 1, 4, 1, 2, 1, 12, 6, 0, 1, 14, 1, 8, 0, 32, 1, 18, 1, 18, 8, 12, 1, 42, 4, 14, 25, 2, 1, 30, 1, 80, 12, 18, 6, 60, 1, 20, 14, 62, 1, 8, 1, 48, 31, 24, 1, 110, 14, 32, 18, 56, 1, 78, 10, 62, 20, 30, 1, 90, 1, 32, 19, 192, 12, 60, 1, 72, 24, 22, 1, 156, 1, 38, 43, 80, 18, 68, 1, 170, 108, 42, 1, 92, 16, 44
Offset: 0

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Author

Antti Karttunen, Feb 11 2024

Keywords

Crossrefs

Cf. A003415, A276085, A276086, A327859, A369964, A370115 (positions of 0's), A370117.

Programs

  • PARI
    A002110(n) = prod(i=1,n,prime(i));
    A276085(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*A002110(primepi(f[k, 1])-1)); };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A370120(n) = { my(u=A276086(A003415(n))); A276085(u/gcd(n, u)); };

Formula

a(n) = A276085(A370117(n)).