A204825 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

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

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

LINKS

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

Eric Weisstein's World of Mathematics, Abundant Number

EXAMPLE

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

MATHEMATICA

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

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).

Sequence in context: A360253 A097320 A332956 * A111592 A111947 A109396

Adjacent sequences: A204822 A204823 A204824 * A204826 A204827 A204828

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Jan 22 2012

STATUS

approved