OFFSET
0,2
MATHEMATICA
a[n_] := Module[{k = 1}, While[!Divisible[DivisorSigma[1, k], EulerPhi[k] + n], k++]; k]; Array[a, 30, 0] (* Amiram Eldar, Dec 10 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
a(1) corrected by Sean A. Irvine, Dec 10 2018
STATUS
approved