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.

A331180 Number of values of k, 1 <= k <= n, with A323910(k) = A323910(n), where A323910 is Dirichlet inverse of deficiency of n.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 3, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 2, 3, 1, 2, 1, 4, 1, 1, 1, 3, 1, 1, 2, 4, 1, 1, 1, 4, 5, 1, 1, 2, 1, 3, 1, 5, 1, 5, 1, 6, 1, 1, 1, 6, 1, 1, 2, 6, 1, 2, 1, 7, 1, 3, 1, 2, 1, 2, 8, 9, 1, 1, 1, 3, 2, 2, 1, 3, 1, 1, 1, 7, 1, 10, 1, 11, 2, 1, 2, 1, 1, 2, 2, 7, 1, 1, 1, 8, 2
Offset: 1

Views

Author

Antti Karttunen, Jan 11 2020

Keywords

Comments

Ordinal transform of A323910.

Crossrefs

Cf. also A331178, A331181.

Programs

  • Mathematica
    f[n_] := 2 n - DivisorSigma[1, n];
    A323910[n_] := A323910[n] = If[n == 1, 1, -Sum[f[n/d] A323910[d], {d, Most@Divisors[n]}]];
    Module[{b}, b[] = 0; a[n] := With[{t = A323910[n]}, b[t] = b[t] + 1]];
    Array[a, 105] (* Jean-François Alcover, Jan 12 2022 *)
  • 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; };
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA033879(n) = (2*n-sigma(n));
    v331180 = ordinal_transform(DirInverse(vector(up_to,n,A033879(n))));
    A331180(n) = v331180[n];

A331182 Number of values of k, 1 <= k <= n, with A083254(k) = A083254(n), where A083254(n) = 2*phi(n) - n.

Original entry on oeis.org

1, 1, 2, 2, 1, 1, 1, 3, 2, 2, 1, 1, 1, 3, 3, 4, 1, 1, 1, 2, 3, 4, 1, 1, 2, 5, 2, 3, 1, 1, 1, 5, 1, 6, 1, 1, 1, 7, 3, 2, 1, 1, 1, 4, 4, 8, 1, 1, 2, 1, 2, 5, 1, 2, 1, 3, 3, 9, 1, 1, 1, 10, 4, 6, 1, 1, 1, 6, 1, 1, 1, 1, 1, 11, 2, 7, 1, 1, 1, 2, 2, 12, 1, 1, 2, 13, 2, 4, 1, 1, 1, 8, 3, 14, 1, 1, 1, 2, 2, 1, 1, 1, 1, 5, 1
Offset: 1

Views

Author

Antti Karttunen, Jan 11 2020

Keywords

Comments

Ordinal transform of A083254.

Crossrefs

Programs

  • Mathematica
    Module[{b}, b[_] = 0;
    a[n_] := With[{t = 2 EulerPhi[n] - n}, b[t] = b[t] + 1]];
    Array[a, 105] (* Jean-François Alcover, Jan 12 2022 *)
  • 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; };
    A083254(n) = (2*eulerphi(n)-n);
    v331182 = ordinal_transform(vector(up_to,n,A083254(n)));
    A331182(n) = v331182[n];

A331184 Number of values of k, 1 <= k <= n, with A318310(k) = A318310(n).

Original entry on oeis.org

1, 2, 1, 3, 1, 1, 1, 4, 1, 2, 1, 1, 1, 1, 1, 5, 1, 1, 1, 1, 2, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 6, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 3, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 4, 1, 1, 1
Offset: 1

Views

Author

Antti Karttunen, Jan 12 2020

Keywords

Comments

Ordinal transform of A318310, or equally, of the ordered pair [A000120(n), A033879(n)], i.e., binary weight of n & deficiency of n.

Crossrefs

Programs

  • PARI
    up_to = 16384;
    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; };
    A318310aux(n) = [hammingweight(n), (2*n) - sigma(n)];
    v331184 = ordinal_transform(vector(up_to,n,A318310aux(n)));
    A331184(n) = v331184[n];
Showing 1-3 of 3 results.