OFFSET
1,1
COMMENTS
All repunit primes are in the sequence. So A004022 is a subsequence of this sequence.
All terms beyond a(3) are coprime to 6, and of course all terms are zerofree (A052382). a(5) > 10^11. - Charles R Greathouse IV, Nov 03 2014
a(5) > 2*10^12. - Giovanni Resta, Aug 30 2018
EXAMPLE
sigma(11735953) = sigma(883*13291) = 11735953 + (13291 + 883 + 1) = 11735953 + 1*1*7*3*5*9*5*3 so 11735953 is in the sequence.
MATHEMATICA
Do[If[DivisorSigma[1, n]-n==Apply[Times, IntegerDigits[n]], Print[n]], {n, 50000000}]
PROG
(PARI) is(n)=my(d=digits(n), p=prod(i=1, #d, d[i])); p>0 && p+n==sigma(n) \\ Charles R Greathouse IV, Nov 03 2014
CROSSREFS
KEYWORD
base,more,nice,nonn
AUTHOR
Farideh Firoozbakht, Oct 27 2008
STATUS
approved