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.

A322871 Ordinal transform of A060681, where A060681(n) = n - A032742(n).

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 1, 3, 1, 1, 2, 1, 1, 1, 1, 3, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 2, 3, 1, 1, 1, 2, 1, 1, 1, 3, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 3, 1, 2, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 4, 1, 1, 2, 2, 1, 1, 2, 3, 1, 1, 1, 1, 1, 1, 3, 2, 1, 1, 1, 3, 2
Offset: 1

Views

Author

Antti Karttunen, Dec 29 2018

Keywords

Crossrefs

Programs

  • Mathematica
    A060681[n_] := n - n/FactorInteger[n][[1, 1]];
    b[_] = 1;
    a[n_] := a[n] = With[{t = A060681[n]}, b[t]++];
    a /@ Range[1, 105] (* Jean-François Alcover, Dec 19 2021 *)
  • PARI
    up_to = 65537;
    ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om,invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om,invec[i],(1+pt))); outvec; };
    A060681(n) = if(1==n,0,(n-(n/vecmin(factor(n)[, 1]))));
    v322871 = ordinal_transform(vector(up_to,n,A060681(n)));
    A322871(n) = v322871[n];

A300721 Möbius transform of A060681, the largest difference between consecutive divisors of n (ordered by size).

Original entry on oeis.org

0, 1, 2, 1, 4, 0, 6, 2, 4, 0, 10, 2, 12, 0, 4, 4, 16, 2, 18, 4, 6, 0, 22, 4, 16, 0, 12, 6, 28, 4, 30, 8, 10, 0, 18, 6, 36, 0, 12, 8, 40, 6, 42, 10, 16, 0, 46, 8, 36, 4, 16, 12, 52, 6, 30, 12, 18, 0, 58, 8, 60, 0, 24, 16, 36, 10, 66, 16, 22, 6, 70, 12, 72, 0, 24, 18, 50, 12, 78, 16, 36, 0, 82, 12, 48, 0, 28, 20, 88, 8, 60, 22, 30, 0, 54, 16
Offset: 1

Views

Author

Antti Karttunen, Mar 11 2018

Keywords

Crossrefs

Cf. A000010, A008683, A060681, A300236, A300722, A322873 (ordinal transform).

Programs

Formula

a(n) = Sum_{d|n} A008683(n/d)*A060681(d).
a(n) = A060681(n) - A300722(n).
a(n) = A000010(n) - A300236(n).

A322874 Ordinal transform of A007431, which is Möbius transform of Euler phi.

Original entry on oeis.org

1, 1, 2, 3, 1, 2, 1, 1, 1, 3, 1, 4, 1, 4, 2, 2, 1, 5, 1, 3, 2, 6, 1, 2, 1, 7, 1, 3, 1, 8, 1, 1, 2, 9, 2, 3, 1, 10, 2, 1, 1, 11, 1, 3, 2, 12, 1, 4, 1, 13, 3, 3, 1, 14, 2, 1, 2, 15, 1, 4, 1, 16, 1, 2, 1, 17, 1, 4, 2, 18, 1, 2, 1, 19, 3, 3, 2, 20, 1, 3, 2, 21, 1, 4, 3, 22, 3, 1, 1, 23, 1, 3, 2, 24, 2, 3, 1, 25, 3, 4, 1, 26, 1, 1, 5
Offset: 1

Views

Author

Antti Karttunen, Dec 29 2018

Keywords

Crossrefs

Programs

  • Mathematica
    A007431[n_] := Sum[EulerPhi[d] MoebiusMu[n/d], {d, Divisors[n]}];
    b[_] = 0;
    a[n_] := a[n] = With[{t = A007431[n]}, b[t] = b[t]+1];
    Array[a, 105] (* Jean-François Alcover, Dec 20 2021 *)
  • PARI
    up_to = 65537;
    ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om,invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om,invec[i],(1+pt))); outvec; };
    A007431(n) = sumdiv(n,d,moebius(n/d)*eulerphi(d));
    v322874 = ordinal_transform(vector(up_to,n,A007431(n)));
    A322874(n) = v322874[n];
Showing 1-3 of 3 results.