A204825 Abundant numbers with even sum of divisors.

12, 20, 24, 30, 40, 42, 48, 54, 56, 60, 66, 70, 78, 80, 84, 88, 90, 96, 102, 104, 108, 112, 114, 120, 126, 132, 138, 140, 150, 156, 160, 168, 174, 176, 180, 186, 192, 198, 204, 208, 210, 216, 220, 222, 224, 228, 234, 240, 246, 252, 258, 260, 264, 270, 272, 276, 280

Offset: 1

Author

Jaroslav Krizek, Jan 22 2012

Keywords

• nonn

Comments

Numbers m from A005101 such that sigma(m) = A000203(m) is even.

Complement of A156903 with respect to A005101 (abundant numbers).

Examples

			Abundant number 12 is in sequence because sigma(12) = 28 (even number).
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Abundant Number

Crossrefs

Cf. A156903 (abundant numbers with odd sum of divisors), A204826 (deficient numbers with odd sum of divisors), A204827 (deficient numbers with even sum of divisors).

Programs

Mathematica

aQ[n_] := EvenQ[(s = DivisorSigma[1, n])] && s > 2n; Select[Range[280], aQ] (* Amiram Eldar, Sep 02 2019 *)