

A204825


Abundant numbers with even sum of divisors.


4



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
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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: A112769 A097320 A332956 * A111592 A111947 A109396
Adjacent sequences: A204822 A204823 A204824 * A204826 A204827 A204828


KEYWORD

nonn


AUTHOR

Jaroslav Krizek, Jan 22 2012


STATUS

approved



