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 A333928 #7 Apr 11 2020 05:36:32 %S A333928 12,18,20,30,36,42,60,66,70,78,84,90,100,102,108,114,120,126,132,138, %T A333928 140,144,150,156,168,174,180,186,196,198,204,210,220,222,228,234,240, %U A333928 246,252,258,260,270,276,282,294,300,306,308,318,324,330,336,340,342,348 %N A333928 Recursive abundant numbers: numbers k such that A333926(k) > 2*k. %H A333928 Amiram Eldar, <a href="/A333928/b333928.txt">Table of n, a(n) for n = 1..10000</a> %e A333928 12 is a term since A333926(12) = 28 > 2 * 12. %t A333928 recDivQ[n_, 1] = True; recDivQ[n_, d_] := recDivQ[n, d] = Divisible[n, d] && AllTrue[FactorInteger[d], recDivQ[IntegerExponent[n, First[#]], Last[#]] &]; recDivs[n_] := Select[Divisors[n], recDivQ[n, #] &]; f[p_, e_] := 1 + Total[p^recDivs[e]]; recDivSum[1] = 1; recDivSum[n_] := Times @@ (f @@@ FactorInteger[n]); Select[Range[350], recDivSum[#] > 2*# &] %Y A333928 Cf. A333926, A333927. %Y A333928 Analogous sequences: A005101, A034683 (unitary), A064597 (nonunitary), A129575 (exponential), A129656 (infinitary), A292982 (bi-unitary). %K A333928 nonn %O A333928 1,1 %A A333928 _Amiram Eldar_, Apr 10 2020