OFFSET
1,1
COMMENTS
The even perfect numbers (A000396) are a subsequence.
The deficient numbers (A005100) in the sequence are 14, 51, 679, 752, 2055, 2651, 4381, 6413, 9809, 9945, 21970, ... - Juri-Stepan Gerasimov, Jul 07 2011
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..600
EXAMPLE
14 is in this sequence because (1*2*7*14) mod (1+2+7+14) = 196 mod 24 = 4 and (1*2*7) mod (1+2+7) = 14 mod 10 = 4.
MATHEMATICA
erQ[n_]:=Module[{divs=Divisors[n], ds=DivisorSigma[1, n]}, Mod[ Times@@ divs, ds] == Mod[ Times@@Most[divs], ds-n]]; Select[Range[2, 30000], erQ] (* Harvey P. Dale, Jun 13 2015 *)
Select[Range[2, 30000], Mod[(p = #^(DivisorSigma[0, #]/2)), (s = DivisorSigma[1, #])] == Mod[p/#, s - #] &] (* Amiram Eldar, Jul 21 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Jun 21 2011
EXTENSIONS
Values from a(4) onwards from R. J. Mathar, Jul 05 2011
STATUS
approved