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 A066226 #9 Sep 26 2019 09:05:05
%S A066226 2,88,328,5128,9075,327688,1310728,2066056,2259976,188186624,
%T A066226 560889856,847020032,1342177288
%N A066226 The sigma(EulerPhi)-perfect numbers, where the set of f-perfect numbers for an arithmetical function f is defined in A066218.
%C A066226 These are all the terms less than 10^5. Problem: Find an expression generating all the terms.
%H A066226 J. Pe, <a href="http://jlpe.tripod.com/gpn/fperfect.htm">On a Generalization of Perfect Numbers</a>, J. Rec. Math., 31(3) (2002-2003), 168-172.
%e A066226 Let f(n) = sigma(EulerPhi(n)). The proper divisors of 88 are {1, 2, 4, 8, 11, 22, 44}; adding their f-values: 1 + 1 + 3 + 7 + 18 + 18 + 42 = 90 = f(88). Hence 88 is a term of the sequence.
%t A066226 f[x_] := DivisorSigma[1, EulerPhi[x]]; Select[ Range[ 1, 10^5], 2 * f[ # ] == Apply[ Plus, Map[ f, Divisors[ # ] ] ] & ]
%Y A066226 Cf. A000010, A000203, A066218.
%K A066226 nonn,more
%O A066226 1,1
%A A066226 _Joseph L. Pe_, Dec 18 2001
%E A066226 a(6)-a(13) from _Amiram Eldar_, Sep 26 2019