A204827 Deficient numbers with even sum of divisors.

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

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

Cf. A000203, A005100, A028983.

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

Adjacent sequences: A204824 A204825 A204826 * A204828 A204829 A204830

Keyword

nonn

Author

Jaroslav Krizek, Jan 22 2012

Status

approved