This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A302125 #13 Jun 03 2018 11:51:35
%S A302125 7,15,29,52,62,182,230,315,344,592,944,998,1155,2012,2570,4028,6710,
%T A302125 15128,19688,20264,30248,36224,38252,40730,43964,52088,90332,96128,
%U A302125 168116,195224,258512,262112,451952,538112,991904,1209632,1237856,1659128,2080544,2085710,2102272,2186132
%N A302125 Numbers whose deficiency is a perfect number.
%C A302125 Subsequence of deficient numbers (A005100) whose deficiency (A033879) is a member of perfect numbers (A000396).
%e A302125 52 is in the sequence since the divisors of 52 are {1, 2, 4, 13, 26 & 52} so d(52) = 98 and 2*52 - 98 = 6, a perfect number.
%t A302125 fQ[n_] := PerfectNumberQ[2n - DivisorSigma[1, n]]; Select[ Range@ 2500000, fQ]
%o A302125 (PARI) for(n=1,25*10^5, d=2*n-sigma(n); d>0&&sigma(d)==2*d&&print1(n ","))
%Y A302125 Cf. A000396 (perfect numbers), A033879 (deficiency), A005100 (deficient numbers), A141548 (subsequence), A301859 (related sequence).
%K A302125 nonn
%O A302125 1,1
%A A302125 _Robert G. Wilson v_ and _Waldemar Puszkarz_, Apr 01 2018