OFFSET
1,1
COMMENTS
This sequence contains the composite number 305635357, so is different from A023200 and A029710 (305635357 is the only composite member of the present sequence below 10^9). - Jud McCranie, Jan 07 2001
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MATHEMATICA
Select[Range[1500], DivisorSigma[1, #]+4==DivisorSigma[1, #+4]&] (* Harvey P. Dale, Nov 04 2011 *)
PROG
(PARI) is(n)=sigma(n)+4==sigma(n+4) \\ Charles R Greathouse IV, Mar 09 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved