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 A088826 #19 Oct 15 2013 22:32:19
%S A088826 12,42,1242,6137440,1385119360,1588268480
%N A088826 Solutions to sigma(n)-2*n = phi(n): abundance of n equals Euler-phi of n.
%C A088826 a(7) > 10^12. - _Donovan Johnson_, Feb 29 2012
%C A088826 10^13 < a(7) <= 479535318548480. Other terms of the form 2^k*5*p*q are 983990190817280, 528322308638228480, 1374972658786140160, 9222951307429806080 and 13732480001814200320. - _Giovanni Resta_, Jul 12 2013
%C A088826 248248256622696037089280 and 29053620223944172891013120 are the next two terms of the form 2^k*5*p*q where p&q are distinct primes. 12, 42 and 1242 are the only terms of one of the three forms 4*p, 2*p*q and 2*p^3*q where p and q are two distinct primes. _Farideh Firoozbakht_, Aug 19 2013
%e A088826 n=1242, sigma(1242)=2880, 2880-2484=396=phi(1242).
%t A088826 Do[If[Equal[DivisorSigma[1, n]-2*n, EulerPhi[n]], Print[n]], {n, 1, 10000000}]
%Y A088826 Cf. A000203, A000010, A077374, A033880.
%K A088826 more,nonn
%O A088826 1,1
%A A088826 _Labos Elemer_, Oct 27 2003
%E A088826 a(5)-a(6) from _Donovan Johnson_, Sep 30 2009