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 A253302 #29 Aug 01 2019 03:47:26
%S A253302 1,16,300,136,50316,186,97748,1352,72318,1340,1652,1356
%N A253302 Smallest integer m such that gcd{x | sum of proper divisors of x is m} is equal to n, when there are at least two such x's.
%C A253302 Only integers m that satisfy A048138(m) > 1 are considered here.
%C A253302 Other known terms with odd indices: a(25)=39926, a(49)=46850.
%C A253302 For terms with even indices see A253303.
%e A253302 For every prime p the sum of proper divisors of p is 1, and the GCD of the primes is 1, so a(1) = 1.
%o A253302 (PARI) build(nb) = {vs = vector(nb); nc = nb^2; forcomposite(n=2, nc, val = sigma(n)-n; if (val <= nb, if (vs[val] == 0, vs[val] = -n, vs[val] = gcd(vs[val], n)););); vs[1] = 1; vs;}
%o A253302 lista() = {vd = build(100000); vmax = 20; vr = vector(vmax); for (ig=1, vmax, for (i=1, #vd, w = vd[i]; if (w ==ig, vr[ig] = i; break;););); for (i=1, #vr, if (vr[i] == 0, break, print1(vr[i], ", ")));}
%Y A253302 Cf. A001065 (sum of proper divisors), A048138, A152454, A253303.
%K A253302 nonn,more
%O A253302 1,2
%A A253302 _Michel Marcus_, Dec 30 2014
%E A253302 a(1)=1 suggested by _Robert Israel_, Jan 01 2015