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.

A348494 a(n) = A348492(n) / A003557(n), where A348492 is the GCD of the arithmetic derivative (A003415) and Pillai's arithmetical function (A018804).

Original entry on oeis.org

1, 1, 1, 2, 1, 5, 1, 1, 1, 1, 1, 4, 1, 3, 1, 2, 1, 7, 1, 12, 5, 1, 1, 1, 1, 15, 3, 4, 1, 1, 1, 1, 7, 1, 3, 2, 1, 3, 1, 1, 1, 1, 1, 12, 1, 5, 1, 2, 1, 3, 5, 4, 1, 9, 1, 1, 1, 1, 1, 2, 1, 3, 1, 2, 9, 1, 1, 12, 1, 1, 1, 1, 1, 3, 1, 4, 3, 1, 1, 2, 1, 1, 1, 2, 11, 15, 1, 35, 1, 1, 5, 12, 1, 1, 3, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1
Offset: 1

Views

Author

Antti Karttunen, Oct 21 2021

Keywords

Crossrefs

Programs

  • Mathematica
    Array[GCD[Total@ GCD[#1, Range[#1]], #1 Total[#2/#1 & @@@ #2]]/Apply[Times, Map[#1^(#2 - 1) & @@ # &, #2]] & @@ {#, FactorInteger[#]} &, 105] (* Michael De Vlieger, Oct 21 2021 *)
  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A003557(n) = (n/factorback(factorint(n)[, 1]));
    A018804(n) = sumdiv(n, d, n*eulerphi(d)/d); \\ From A018804
    A348492(n) = gcd(A003415(n), A018804(n));
    A348494(n) = (A348492(n)/A003557(n));

Formula

a(n) = gcd(A342001(n), A347128(n)).
a(n) = A348492(n) / A003557(n), where A348492(n) = gcd(A003415(n), A018804(n)).

A348495 a(n) = gcd(A018804(n), A347130(n)), where A347130 is the Dirichlet convolution of the identity function with the arithmetic derivative of n (A003415), and A018804 is Pillai's arithmetical function.

Original entry on oeis.org

1, 1, 1, 2, 1, 5, 1, 4, 3, 1, 1, 8, 1, 3, 1, 16, 1, 63, 1, 72, 5, 1, 1, 4, 5, 15, 27, 8, 1, 1, 1, 16, 7, 1, 3, 6, 1, 3, 1, 4, 1, 1, 1, 24, 9, 5, 1, 80, 7, 15, 5, 8, 1, 81, 1, 4, 1, 1, 1, 24, 1, 3, 3, 32, 9, 1, 1, 24, 1, 1, 1, 12, 1, 3, 5, 8, 3, 1, 1, 16, 27, 1, 1, 8, 11, 15, 1, 140, 1, 9, 5, 72, 1, 1, 3, 16, 1
Offset: 1

Views

Author

Antti Karttunen, Oct 21 2021

Keywords

Crossrefs

Programs

  • Mathematica
    Table[GCD[Total@ GCD[n, Range[n]], DivisorSum[n, #*(If[# < 2, 0, # Total[#2/#1 & @@@ FactorInteger[#]]] &[n/#]) &]], {n, 97}] (* Michael De Vlieger, Oct 21 2021 *)
  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A018804(n) = sumdiv(n, d, n*eulerphi(d)/d); \\ From A018804
    A347130(n) = sumdiv(n,d,d*A003415(n/d));
    A348495(n) = gcd(A018804(n), A347130(n));

Formula

a(n) = gcd(A018804(n), A347130(n)).
a(n) = A003557(n) * A348496(n).

A348500 a(n) = A348494(A276086(n)).

Original entry on oeis.org

1, 1, 1, 5, 1, 7, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 1, 1, 1, 3, 5, 1, 1, 1, 3, 1, 1, 13, 1, 1, 1, 1, 1, 1, 1, 1, 13, 3, 1, 1, 1, 1, 3, 1, 1, 1, 13, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 19, 1, 1, 19, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1
Offset: 0

Views

Author

Antti Karttunen, Oct 21 2021

Keywords

Crossrefs

Programs

  • Mathematica
    Block[{b = MixedRadix[Reverse@ Prime@ Range@ 12]}, Map[GCD[Total@GCD[#1, Range[#1]], #1 Total[#2/#1 & @@@ #2]]/Apply[Times, Map[#1^(#2 - 1) & @@ # &, #2]] & @@ {#, FactorInteger[#]} &, Table[Function[k, Times @@ Power @@@ # &@ Transpose@ {Prime@ Range@ Length@ k, Reverse@ k}]@ IntegerDigits[n, b], {n, 0, 105}] ] ] (* Michael De Vlieger, Oct 21 2021 *)
  • PARI
    \\ Needs also code from A348494:
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A348500(n) = A348494(A276086(n));

Formula

a(n) = A348494(A276086(n)), where A348494(n) = A348492(n) / A003557(n).

A348497 a(n) = gcd(A003415(n), A347130(n)), where A003415 is the arithmetic derivative and A347130 is its Dirichlet convolution with the identity function.

Original entry on oeis.org

0, 1, 1, 2, 1, 5, 1, 12, 3, 7, 1, 16, 1, 9, 8, 16, 1, 21, 1, 24, 10, 13, 1, 44, 5, 15, 27, 32, 1, 31, 1, 80, 14, 19, 12, 30, 1, 21, 16, 68, 1, 41, 1, 48, 39, 25, 1, 112, 7, 45, 20, 56, 1, 81, 16, 92, 22, 31, 1, 92, 1, 33, 51, 96, 18, 61, 1, 72, 26, 59, 1, 156, 1, 39, 55, 80, 18, 71, 1, 176, 54, 43, 1, 124, 22, 45
Offset: 1

Views

Author

Antti Karttunen, Oct 23 2021

Keywords

Crossrefs

Programs

  • Mathematica
    f[n_] := If[n < 2, 0, n Total[#2/#1 & @@@ FactorInteger[n]]]; Table[GCD[f[n], DivisorSum[n, # f[n/#] &]], {n, 86}] (* Michael De Vlieger, Oct 25 2021 *)
  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A347130(n) = sumdiv(n,d,d*A003415(n/d));
    A348497(n) = gcd(A003415(n), A347130(n));

Formula

a(n) = gcd(A003415(n), A347130(n)).
a(n) = A003557(n) * A348498(n).

A348493 a(n) = A003415(n) / gcd(A003415(n), A018804(n)), where A003415 is the arithmetic derivative and A018804 is Pillai's arithmetical function.

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 1, 3, 2, 7, 1, 2, 1, 3, 8, 2, 1, 1, 1, 1, 2, 13, 1, 11, 2, 1, 1, 4, 1, 31, 1, 5, 2, 19, 4, 5, 1, 7, 16, 17, 1, 41, 1, 2, 13, 5, 1, 7, 2, 3, 4, 7, 1, 1, 16, 23, 22, 31, 1, 23, 1, 11, 17, 3, 2, 61, 1, 3, 26, 59, 1, 13, 1, 13, 11, 10, 6, 71, 1, 11, 4, 43, 1, 31, 2, 3, 32, 1, 1, 41, 4, 4, 34, 49, 8
Offset: 1

Views

Author

Antti Karttunen, Oct 21 2021

Keywords

Crossrefs

Programs

  • Mathematica
    Array[#2/GCD[#1, #2] & @@ {Total@ GCD[#, Range[#]], If[# < 2, 0, # Total[#2/#1 & @@@ FactorInteger[#]]]} &, 95] (* Michael De Vlieger, Oct 21 2021 *)
  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A018804(n) = sumdiv(n, d, n*eulerphi(d)/d); \\ From A018804
    A348493(n) = { my(u=A003415(n)); (u/gcd(u,A018804(n))); };

Formula

a(n) = A003415(n) / A348492(n).
Showing 1-5 of 5 results.