OFFSET
1,1
LINKS
Robert G. Wilson v, Table of n, a(n) for n = 1..10556
MATHEMATICA
k = 1; lst = {}; While[k < 100001, If [ !PrimeQ@ k && PrimeQ[ DivisorSigma[0, k^(k -1)]], AppendTo[lst, k]]; k++]; lst (* or *)
mx = 10^6; Union@ Flatten@ Reap[ Do[ Sow@ Select[ Prime[ Range[ PrimePi[ mx^(1/e) ]]]^e, PrimeQ[1 + e (#-1)] &], {e, 2, Log2[mx]}]][[2, 1]] (* Giovanni Resta, Mar 10 2017 *)
PROG
(PARI) is(n)=!isprime(n) && ispseudoprime(numdiv(n^(n-1))) \\ Charles R Greathouse IV, Mar 10 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Mar 10 2017
STATUS
approved