A088829 Even numbers with even abundance.

6, 10, 12, 14, 20, 22, 24, 26, 28, 30, 34, 38, 40, 42, 44, 46, 48, 52, 54, 56, 58, 60, 62, 66, 68, 70, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 130, 132, 134, 136, 138, 140, 142, 146, 148, 150, 152

Offset: 1

Author

Labos Elemer, Oct 28 2003

Keywords

• nonn

Comments

Odd numbers with odd abundance are in A016754. Odd numbers with even abundance are in A088828. Even numbers with odd abundance are in A088827.

Examples

			Even perfect numbers are here.
n=10: sigma[10]=18, abundance=18-20=-2<0;
n=12: sigma[12]=28, abundance=28-24=+4>0.
sigma[n] is also even number; sign of abundance:<=>0.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A016754, A088827-A088828, A088830.

Programs

Mathematica

Do[s=DivisorSigma[1, n]-2*n; If[ !OddQ[s]&&!OddQ[n], Print[{n, s}]], {n, 1, 1000}]