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.

Showing 1-2 of 2 results.

A369912 a(n) = Sum_{p|n, p prime} p^sopf(n/p).

Original entry on oeis.org

0, 1, 1, 4, 1, 17, 1, 4, 27, 57, 1, 41, 1, 177, 368, 4, 1, 251, 1, 153, 2530, 2169, 1, 41, 3125, 8361, 27, 561, 1, 5568, 1, 4, 178478, 131361, 94932, 275, 1, 524649, 1596520, 153, 1, 37514, 1, 8313, 6686, 8389137, 1, 41, 823543, 78157, 129145076, 32937, 1, 251
Offset: 1

Views

Author

Wesley Ivan Hurt, Feb 05 2024

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := Sum[p, {p, Select[Divisors[n], PrimeQ]}]; Table[DivisorSum[n, #^a[n/#] &, PrimeQ[#] &], {n, 80}]

Formula

a(p^k) = p^(p-p*floor(1/k)) for p prime and k>=1. - Wesley Ivan Hurt, Jul 09 2025

A369914 a(n) = n * Sum_{p|n, p prime} sopf(n/p) / p.

Original entry on oeis.org

0, 0, 0, 4, 0, 13, 0, 8, 9, 29, 0, 38, 0, 53, 34, 16, 0, 57, 0, 78, 58, 125, 0, 76, 25, 173, 27, 134, 0, 220, 0, 32, 130, 293, 74, 150, 0, 365, 178, 156, 0, 366, 0, 294, 147, 533, 0, 152, 49, 195, 298, 398, 0, 171, 146, 268, 370, 845, 0, 500, 0, 965, 237, 64, 194
Offset: 1

Views

Author

Wesley Ivan Hurt, Feb 05 2024

Keywords

Comments

Dirichlet convolution of c(n) and n * sopf(n), where c = A010051. - Wesley Ivan Hurt, Jul 10 2025

Crossrefs

Programs

  • Mathematica
    a[n_] := Sum[p, {p, Select[Divisors[n], PrimeQ]}]; Table[n*DivisorSum[n, a[n/#]/# &, PrimeQ[#] &], {n, 80}]

Formula

a(p^k) = p^k * (1 - floor(1/k)) for p prime and k>=1. - Wesley Ivan Hurt, Jul 09 2025
a(n) = n * Sum_{d|n} c(d) * sopf(n/d) / d, where c = A010051. - Wesley Ivan Hurt, Jul 10 2025
Showing 1-2 of 2 results.