OFFSET
1,2
COMMENTS
Also, numbers n such that B(n)*n == 9 (mod n), where B(n) is the n-th Bernoulli number. Equivalently, SUM[prime p, (p-1) divides n] n/p == -9 (mod n). There are no other terms below 10^30. - Max Alekseyev, Aug 26 2013
MATHEMATICA
Select[Range[10000], Mod[Sum[PowerMod[i, #, #], {i, #}], #] == Mod[9, #] &]
PROG
(PARI) is(n)=Mod(sumdiv(n, d, if(isprime(d+1), n/(d+1))), n)==-9 \\ Charles R Greathouse IV, Nov 13 2013
CROSSREFS
KEYWORD
nonn,more
AUTHOR
José María Grau Ribas, Jun 24 2013
EXTENSIONS
1,2,9 prepended by Max Alekseyev, Aug 26 2013
STATUS
approved