OFFSET
1,2
COMMENTS
a(18) > 10^13, if it exists. - Giovanni Resta, Jan 05 2020
EXAMPLE
The divisors of 21 are 1,3,7,21 and the 21st prime is 73. 1+3+7+21+73 = 105, which is divisible by 21.
MATHEMATICA
Select[Range[10^8], Mod[Prime[ # ] + Plus @@ Divisors[ # ], # ] == 0 &] (* Ray Chandler, Jan 24 2006 *)
PROG
(PARI) p=2; for(n=1, 100000000, if( (sigma(n)+p) % n == 0, print(n) ) ; p=nextprime(p+1) ; ) \\ R. J. Mathar, Feb 11 2008
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Ray G. Opao, Nov 07 2005
EXTENSIONS
a(13)-a(15) from Donovan Johnson, Apr 22 2008
New name from Michel Marcus, Dec 10 2019
a(16)-a(17) from Giovanni Resta, Dec 12 2019
STATUS
approved