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%I #15 Nov 02 2023 23:42:22
%S 72,240,672,800,2240,4224,5184,6272,9984,14080,17280,33280,39424,
%T 48384,52224,57600,93184,116736,161280,174080,192000,247808,304128,
%U 373248,389120,451584,487424,537600,565248,585728,640000,718848
%N Droll numbers: sum of even prime divisors equals sum of odd prime divisors.
%H Donovan Johnson, <a href="/A019507/b019507.txt">Table of n, a(n) for n = 1..1000</a>
%F These are numbers k such that A366839(k) = A366840(k). - _Gus Wiseman_, Oct 25 2023
%e 6272 = 2*2*2*2*2*2*2*7*7 is droll since 2+2+2+2+2+2+2 = 14 = 7+7.
%o (PARI) isok(n) = {if (n % 2, return (0)); f = factor(n); return (2*f[1,2] == sum(i=2, #f~, f[i,1]*f[i,2]));} \\ _Michel Marcus_, Jun 21 2013
%Y For count instead of sum we have A072978.
%Y Partitions of this type are counted by A239261, without zero terms A249914.
%Y For prime indices instead of factors we have A366748, zeros of A366749.
%Y The LHS is A366839, for indices A366531, triangle A113686.
%Y The RHS is A366840, for indices A366528, triangle A113685.
%Y A000009 counts partitions into odd parts, ranks A066208.
%Y A035363 counts partitions into even parts, ranks A066207.
%Y A112798 lists prime indices, length A001222, sum A056239.
%Y A257991 counts odd prime indices, even A257992.
%Y A300061 lists numbers with even sum of prime indices, odd A300063.
%Y Cf. A028260, A045931, A100367, A106529, A195017, A239241, A241638, A325698, A325700, A366533.
%K nonn
%O 1,1
%A Mario Velucchi (mathchess(AT)velucchi.it)
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