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 A063806 #7 Sep 18 2015 13:59:17
%S A063806 4,6,8,9,10,12,14,15,18,20,21,22,24,25,26,27,28,30,32,33,34,35,38,39,
%T A063806 40,42,44,45,46,49,50,51,52,54,55,56,57,58,60,62,63,65,66,68,69,70,72,
%U A063806 74,75,76,77,78,82,84,85,86,87,88,90,91,92,93,94,95,96,98,99,102,104
%N A063806 Numbers with a prime number of proper divisors.
%H A063806 Harry J. Smith, <a href="/A063806/b063806.txt">Table of n, a(n) for n = 1..1000</a>
%e A063806 15 has three proper divisors {1,3,5} and so is on the list; 16 has four {1,2,4,8} and so is not; 17 has one {1} and so is not; 18 has five {1,2,3,6,9} and so is.
%o A063806 (PARI) n=0; for (m=1, 10^9, if(isprime(numdiv(m) - 1), write("b063806.txt", n++, " ", m); if (n==1000, break))) \\ _Harry J. Smith_, Aug 31 2009
%o A063806 (PARI) is(n)=isprime(numdiv(n)-1) \\ _Charles R Greathouse IV_, Sep 18 2015
%Y A063806 A subset of A002808. Cf. A009087, A032741.
%K A063806 nonn
%O A063806 1,1
%A A063806 _Henry Bottomley_, Aug 20 2001