OFFSET
1,2
MAPLE
with(numtheory):
b:= proc(n) option remember; nops(invphi(n)) end:
a:= proc(n) option remember; `if`(n=0, 1/2, add(
a(n-j)*add(d*b(d), d=divisors(j)), j=1..n)/n)
end:
seq(a(n), n=1..40); # Alois P. Heinz, Feb 19 2021
MATHEMATICA
terms = 40;
S[m_] := S[m] = CoefficientList[Product[1/(1 - x^EulerPhi[k]),
{k, 1, m*terms}] + O[x]^(terms+1), x]/2 // Rest;
S[m = 1];
S[m++];
While[S[m] != S[m-1], m++];
S[m] (* Jean-François Alcover, May 12 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Feb 19 2021
STATUS
approved
