OFFSET
1,2
COMMENTS
EXAMPLE
Number 12 is in the sequence because 12 divides 3*sigma(12) = 3*28.
MAPLE
select(n -> 3*numtheory:-sigma(n) mod n = 0, [$1..10^6]); # Robert Israel, Aug 26 2014
MATHEMATICA
a245774[n_Integer] := Select[Range[n], Divisible[3*DivisorSigma[1, #], #] == True &]; a245774[10^7] (* Michael De Vlieger, Aug 27 2014 *)
PROG
(Magma) [n: n in [1..3000000] | Denominator(3*(SumOfDivisors(n))/n) eq 1]
(PARI)
for(n=1, 10^9, if((3*sigma(n))%n==0, print1(n, ", "))) \\ Derek Orr, Aug 26 2014
CROSSREFS
Cf. A272027 (3*sigma(n)).
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Aug 26 2014
STATUS
approved