OFFSET
1,2
MATHEMATICA
a[n_] := Module[{k = n}, While[! Divisible[DivisorSigma[1, k], EulerPhi[k]], k += n]; k]; Array[a, 50] (* Amiram Eldar, Dec 10 2018 *)
PROG
(PARI) apply( A015756(n)=forstep(k=n, oo, n, sigma(k)%eulerphi(k)||return(k)), [1..50]) \\ M. F. Hasler, Dec 10 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
a(23) corrected by Sean A. Irvine, Dec 09 2018
Definition corrected by Sean A. Irvine and M. F. Hasler, Dec 10 2018
STATUS
approved