OFFSET
1,2
FORMULA
MATHEMATICA
gradus[n_] := 1 + Plus @@ ((First[#] - 1) * Last[#] & /@ FactorInteger[n]); a[n_] := EulerPhi[(g = gradus[n])] - MoebiusMu[g]; Array[a, 76] (* Amiram Eldar, Nov 03 2019 *)
PROG
(PARI) g(n) = my(f = factor(n)); sum(k=1, #f~, (f[k, 1]-1)*f[k, 2])+ 1; \\ A275314
a(n) = my(gn = g(n)); eulerphi(gn) - moebius(gn); \\ Michel Marcus, Nov 04 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Daniel Hoyt, Nov 03 2019
STATUS
approved