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 A231815 #10 Apr 02 2016 12:15:15
%S A231815 30,51319,3882139,289022911,674910259,991523479,1893583519,4550912389,
%T A231815 9761467669,16721570539,28685399311,72886214809,77372307511,
%U A231815 82720376839,98685849571,173850108931,220038912319,229352039821,240313142749,257401051861,428178002569
%N A231815 Squarefree numbers (A005117) of the form p*q*r with prime factors p, q, r with q = 2*p-1 and r = 2*q-1.
%C A231815 Squarefree numbers of the form p*q*r, where p < q < r = primes with q = 2*p - 1 and r = 2*q - 1; that is, r = 4*p - 3.
%C A231815 These numbers are divisible by the arithmetic mean of their proper divisors.
%H A231815 Harvey P. Dale, <a href="/A231815/b231815.txt">Table of n, a(n) for n = 1..1000</a>
%e A231815 3882139 = 79*157*313; 157 = 2*79 - 1; 313 = 2*157 - 1.
%t A231815 t = {}; p = 1; Do[While[p = NextPrime[p]; ! (PrimeQ[p2 = 2 p - 1] && PrimeQ[p3 = 2 p2 - 1])]; AppendTo[t, p*p2*p3], {30}]; t (* _T. D. Noe_, Nov 15 2013 *)
%t A231815 3#-10#^2+8#^3&/@Select[Prime[Range[600]],AllTrue[{2#-1,4#-3},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Apr 02 2016 *)
%Y A231815 Cf. A005117, A057326, A000040, A231814, A231816.
%Y A231815 Cf. A057326 (first member of a prime triple in a 2p-1 progression).
%K A231815 nonn
%O A231815 1,1
%A A231815 _Jaroslav Krizek_, Nov 13 2013