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 1-5 of 5 results.

A351945 a(n) = A342001(A181819(n)).

Original entry on oeis.org

0, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 5, 1, 2, 2, 1, 1, 5, 1, 5, 2, 2, 1, 7, 1, 2, 1, 5, 1, 3, 1, 1, 2, 2, 2, 2, 1, 2, 2, 7, 1, 3, 1, 5, 5, 2, 1, 9, 1, 5, 2, 5, 1, 7, 2, 7, 2, 2, 1, 8, 1, 2, 5, 1, 2, 3, 1, 5, 2, 3, 1, 8, 1, 2, 5, 5, 2, 3, 1, 9, 1, 2, 1, 8, 2, 2, 2, 7, 1, 8, 2, 5, 2, 2, 2, 13, 1, 5, 5, 2, 1, 3, 1, 7, 3
Offset: 1

Views

Author

Antti Karttunen, Apr 02 2022

Keywords

Crossrefs

Programs

Formula

a(n) = A342001(A181819(n)) = A351942(n) / A351944(n).

A353379 Primepi-based variant of the arithmetic derivative applied to the prime shadow of n.

Original entry on oeis.org

0, 1, 1, 2, 1, 4, 1, 3, 2, 4, 1, 7, 1, 4, 4, 4, 1, 7, 1, 7, 4, 4, 1, 11, 2, 4, 3, 7, 1, 12, 1, 5, 4, 4, 4, 12, 1, 4, 4, 11, 1, 12, 1, 7, 7, 4, 1, 15, 2, 7, 4, 7, 1, 11, 4, 11, 4, 4, 1, 20, 1, 4, 7, 6, 4, 12, 1, 7, 4, 12, 1, 19, 1, 4, 7, 7, 4, 12, 1, 15, 4, 4, 1, 20, 4, 4, 4, 11, 1, 20, 4, 7, 4, 4, 4, 21, 1, 7, 7
Offset: 1

Views

Author

Antti Karttunen, Apr 28 2022

Keywords

Crossrefs

Cf. also A351942.

Programs

  • Maple
    a:= n-> (m-> m*add(i[2]*numtheory[pi](i[1])/i[1], i=ifactors(m)[2]))
            (mul(ithprime(i[2]), i=ifactors(n)[2])):
    seq(a(n), n=1..120);  # Alois P. Heinz, Apr 28 2022
  • Mathematica
    a[n_] := If[n == 1, 0, #*Sum[i[[2]]*PrimePi[i[[1]]]/i[[1]], {i, FactorInteger[#]}]]&[Product[Prime[i[[2]]], {i, FactorInteger[n]}]];
    Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Jan 29 2025, after Alois P. Heinz *)
  • PARI
    A181819(n) = factorback(apply(e->prime(e),(factor(n)[,2])));
    A258851(n) = (n*sum(i=1, #n=factor(n)~, n[2, i]*primepi(n[1, i])/n[1, i])); \\ From A258851
    A353379(n) = A258851(A181819(n));

Formula

a(n) = A258851(A181819(n)).

A353576 Arithmetic derivative applied to the prime shadow of the primorial base exp-function: a(n) = A003415(A181819(A276086(n))).

Original entry on oeis.org

0, 1, 1, 4, 1, 5, 1, 4, 4, 12, 5, 16, 1, 5, 5, 16, 6, 21, 1, 7, 7, 24, 8, 31, 1, 9, 9, 32, 10, 41, 1, 4, 4, 12, 5, 16, 4, 12, 12, 32, 16, 44, 5, 16, 16, 44, 21, 60, 7, 24, 24, 68, 31, 92, 9, 32, 32, 92, 41, 124, 1, 5, 5, 16, 6, 21, 5, 16, 16, 44, 21, 60, 6, 21, 21, 60, 27, 81, 8, 31, 31, 92, 39, 123, 10, 41, 41, 124
Offset: 0

Views

Author

Antti Karttunen, Apr 30 2022

Keywords

Crossrefs

Cf. A060735 (positions of 1's).
Cf. also A353575 which has quite a similar scatter plot, while on the contrast, A353577 has a very different look, explained by the contribution of A353524.

Programs

Formula

a(n) = A353524(n) * A353577(n).

A353577 Arithmetic derivative without its inherited divisor applied to the prime shadow of the primorial base exp-function: a(n) = A342001(A181819(A276086(n))).

Original entry on oeis.org

0, 1, 1, 2, 1, 5, 1, 2, 2, 3, 5, 8, 1, 5, 5, 8, 2, 7, 1, 7, 7, 12, 8, 31, 1, 9, 9, 16, 10, 41, 1, 2, 2, 3, 5, 8, 2, 3, 3, 4, 8, 11, 5, 8, 8, 11, 7, 10, 7, 12, 12, 17, 31, 46, 9, 16, 16, 23, 41, 62, 1, 5, 5, 8, 2, 7, 5, 8, 8, 11, 7, 10, 2, 7, 7, 10, 3, 9, 8, 31, 31, 46, 13, 41, 10, 41, 41, 62, 17, 55, 1, 7, 7, 12, 8
Offset: 0

Views

Author

Antti Karttunen, Apr 30 2022

Keywords

Crossrefs

Cf. A060735 (positions of 1's).
Cf. also A342002, A351954 (similar or analogous definitions).

Programs

Formula

a(n) = A353576(n) / A353524(n).

A351943 a(n) = A069359(A181819(n)).

Original entry on oeis.org

0, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 5, 1, 2, 2, 1, 1, 5, 1, 5, 2, 2, 1, 7, 1, 2, 1, 5, 1, 4, 1, 1, 2, 2, 2, 3, 1, 2, 2, 7, 1, 4, 1, 5, 5, 2, 1, 9, 1, 5, 2, 5, 1, 7, 2, 7, 2, 2, 1, 10, 1, 2, 5, 1, 2, 4, 1, 5, 2, 4, 1, 8, 1, 2, 5, 5, 2, 4, 1, 9, 1, 2, 1, 10, 2, 2, 2, 7, 1, 10, 2, 5, 2, 2, 2, 13, 1, 5, 5, 3, 1, 4, 1, 7, 4
Offset: 1

Views

Author

Antti Karttunen, Apr 02 2022

Keywords

Crossrefs

Coincides with A351942 on the positions given by A130091.

Programs

Showing 1-5 of 5 results.