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 1-3 of 3 results.

A373459 Expansion of Sum_{p prime} x^p/(1 - (p*x)^p).

Original entry on oeis.org

0, 1, 1, 4, 1, 43, 1, 64, 729, 3381, 1, 20707, 1, 827639, 10297066, 16384, 1, 14414443, 1, 30517840269, 678610493338, 285312719187, 1, 10464547507, 95367431640625, 302875123369469, 282429536481, 558545864150392871, 1, 298030849742873568, 1, 1073741824
Offset: 1

Views

Author

Seiichi Manyama, Jun 06 2024

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_]:=Sum[Boole[PrimeQ[d]]d^(n-d),{d,Divisors[n]}]; Array[a,32] (* Stefano Spezia, Mar 30 2025 *)
  • PARI
    a(n) = sumdiv(n, d, isprime(d)*d^(n-d));

Formula

a(n) = Sum_{p|n prime} p^(n - p).
If p is prime, a(p) = 1.

A382512 Expansion of Sum_{p prime} x^p / (1 - x^p)^p.

Original entry on oeis.org

0, 1, 1, 2, 1, 6, 1, 4, 6, 10, 1, 16, 1, 14, 30, 8, 1, 30, 1, 45, 56, 22, 1, 48, 70, 26, 45, 98, 1, 196, 1, 16, 132, 34, 420, 96, 1, 38, 182, 350, 1, 588, 1, 308, 615, 46, 1, 160, 924, 740, 306, 481, 1, 198, 2002, 1744, 380, 58, 1, 1605, 1, 62, 3234, 32, 3640
Offset: 1

Views

Author

Ilya Gutkovskiy, Mar 30 2025

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 65; CoefficientList[Series[Sum[x^Prime[k]/(1 - x^Prime[k])^Prime[k], {k, 1, nmax}], {x, 0, nmax}], x] // Rest

Formula

a(n) = Sum_{p|n, p prime} binomial(n/p+p-2, p-1).

A382513 Expansion of Sum_{p prime} p * x^p / (1 - p * x^p).

Original entry on oeis.org

0, 2, 3, 4, 5, 17, 7, 16, 27, 57, 11, 145, 13, 177, 368, 256, 17, 1241, 19, 1649, 2530, 2169, 23, 10657, 3125, 8361, 19683, 18785, 29, 107442, 31, 65536, 178478, 131361, 94932, 793585, 37, 524649, 1596520, 1439201, 41, 6997770, 43, 4208945, 16302032
Offset: 1

Views

Author

Ilya Gutkovskiy, Mar 30 2025

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 45; CoefficientList[Series[Sum[Prime[k] x^Prime[k]/(1 - Prime[k] x^Prime[k]), {k, 1, nmax}], {x, 0, nmax}], x] // Rest

Formula

a(n) = Sum_{p|n, p prime} p^(n/p).
Showing 1-3 of 3 results.