login
A204827
Deficient numbers with even sum of divisors.
4
3, 5, 7, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 26, 27, 29, 31, 33, 34, 35, 37, 38, 39, 41, 43, 44, 45, 46, 47, 51, 52, 53, 55, 57, 58, 59, 61, 62, 63, 65, 67, 68, 69, 71, 73, 74, 75, 76, 77, 79, 82, 83, 85, 86, 87, 89, 91, 92, 93, 94, 95, 97, 99, 101, 103
OFFSET
1,1
COMMENTS
Numbers m from A005100 such that sigma(m) = A000203(m) is even.
Complement of A204826 with respect to A005100 (deficient numbers).
LINKS
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
Cf. A156903 (abundant numbers with odd sum of divisors), A204825 (abundant numbers with even sum of divisors), A204826 (deficient numbers with odd sum of divisors).
Sequence in context: A352487 A340787 A286607 * A366882 A168252 A071561
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jan 22 2012
STATUS
approved