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Even numbers with even abundance.
6

%I #8 Sep 21 2019 06:55:18

%S 6,10,12,14,20,22,24,26,28,30,34,38,40,42,44,46,48,52,54,56,58,60,62,

%T 66,68,70,74,76,78,80,82,84,86,88,90,92,94,96,102,104,106,108,110,112,

%U 114,116,118,120,122,124,126,130,132,134,136,138,140,142,146,148,150,152

%N Even numbers with even abundance.

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

%H Amiram Eldar, <a href="/A088829/b088829.txt">Table of n, a(n) for n = 1..10000</a>

%e Even perfect numbers are here.

%e n=10: sigma[10]=18, abundance=18-20=-2<0;

%e n=12: sigma[12]=28, abundance=28-24=+4>0.

%e sigma[n] is also even number; sign of abundance:<=>0.

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

%Y Cf. A016754, A088827-A088828, A088830.

%K nonn

%O 1,1

%A _Labos Elemer_, Oct 28 2003