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 A064938 #9 Jun 19 2018 05:16:45
%S A064938 1,4,6,8,10,12,14,20,24,42,48,60,63,70,72,80,84,108,120,124,126,153,
%T A064938 156,182,240,246,264,286,327,372,374,440,492,516,552,1008,1053,1664,
%U A064938 1941,2160,2494,3048,3741,4116,4136,4144,4152,5106,5698,6012,6458,6459
%N A064938 Nonprimes k such that k divides prime(k)^2 - 1.
%H A064938 Harry J. Smith, <a href="/A064938/b064938.txt">Table of n, a(n) for n = 1..160</a>
%t A064938 Select[ Range[10^4], !PrimeQ[ # ] && GCD[ #, Prime[ # ]^2 - 1] == # & ]
%o A064938 (PARI) { default(primelimit, 4294965247); n=0; for (m=1, 10^9, if (isprime(m), next); if (gcd(m, prime(m)^2 - 1) == m, write("b064938.txt", n++, " ", m); if (n==160, return)) ) } \\ _Harry J. Smith_, Sep 30 2009
%Y A064938 Cf. A064830.
%K A064938 easy,nonn
%O A064938 1,2
%A A064938 _Robert G. Wilson v_, Oct 26 2001