OFFSET
1,1
COMMENTS
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Deficient Number
EXAMPLE
Deficient number 15 is in sequence because sigma(15) = 24 (even number).
MATHEMATICA
dnesQ[n_]:=Module[{s=DivisorSigma[1, n]}, s<2n&&EvenQ[s]]; Select[ Range[ 120], dnesQ] (* Harvey P. Dale, Nov 23 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jan 22 2012
STATUS
approved