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

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

1,3

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

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 *)

Prog

(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];

Crossrefs

Cf. A007431, A081373, A303756, A322873.

Sequence in context: A251046 A064529 A338263 * A091654 A127246 A106038

Adjacent sequences: A322871 A322872 A322873 * A322875 A322876 A322877

Keyword

nonn

Author

Antti Karttunen, Dec 29 2018

Status

approved