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Odd abundant numbers whose abundance is even.
2

%I #12 Jan 14 2022 06:34:07

%S 945,1575,2205,2835,3465,4095,4725,5355,5775,5985,6435,6615,6825,7245,

%T 7425,7875,8085,8415,8505,8925,9135,9555,9765,10395,11655,12285,12705,

%U 12915,13545,14175,14805,15015,15435,16065,16695,17325,17955,18585

%N Odd abundant numbers whose abundance is even.

%C This is a subsequence of the odd abundant numbers, A005231. The first term in A005231 but not in this sequence is 11025.

%H Amiram Eldar, <a href="/A174865/b174865.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1989 from T. D. Noe)

%t goodQ[n_] := Module[{ds=DivisorSigma[1,n]}, ds>2n && EvenQ[ds]]; Select[Range[1,1000000,2], goodQ]

%Y Cf. A156942 (Odd abundant numbers whose abundance is odd).

%Y Cf. A005231, A033880.

%K nonn

%O 1,1

%A _T. D. Noe_, Mar 31 2010