OFFSET
1,4
COMMENTS
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
FORMULA
a(n) <= A344773(n).
MATHEMATICA
psi[n_] := If[n= 1, 1, Times@@((#1+1)*#1^(#2-1)& @@@ FactorInteger[n])];
A342915[n_] := GCD[n+1, psi[n]];
b[_] = 0;
a[n_] := a[n] = With[{t = A342915[n]}, b[t] = b[t]+1];
Array[a, 105] (* Jean-François Alcover, Dec 22 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; };
A001615(n) = if(1==n, n, my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1)));
v344771 = ordinal_transform(vector(up_to, n, A342915(n)));
A344771(n) = v344771[n];
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 31 2021
STATUS
approved