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 A065861 #10 Jun 17 2018 01:59:43
%S A065861 0,0,1,1,0,2,3,0,2,0,1,4,0,1,2,6,0,6,0,1,2,8,0,2,3,4,6,4,5,2,4,5,6,7,
%T A065861 8,6,7,8,9,6,8,6,7,8,9,6,8,9,10,12,14,11,12,13,14,0,1,14,16,13,14,15,
%U A065861 16,0,1,16,17,18,0,16,18,15,16,18,20,0,1,20,0,1,2,22,0,1,2,3,4,0,1,2,3,4
%N A065861 Remainder when the n-th composite number is divided by pi(n), the number of primes not exceeding n.
%H A065861 Harry J. Smith, <a href="/A065861/b065861.txt">Table of n, a(n) for n = 2..1000</a>
%F A065861 a(n) = A002808(n) mod A000720(n).
%e A065861 n=100, c(100)=133, pi(100)=25, a(100)=8 because 133 = 5*25 + 8.
%o A065861 (PARI) Composite(n) = { local(k); k=n + primepi(n) + 1; while (k != n + primepi(k) + 1, k = n + primepi(k) + 1); return(k) } { for (n = 2, 1000, a=Composite(n)%primepi(n); write("b065861.txt", n, " ", a) ) } \\ _Harry J. Smith_, Nov 02 2009
%Y A065861 Cf. A002808, A000720, A065855-A065864.
%K A065861 nonn
%O A065861 2,6
%A A065861 _Labos Elemer_, Nov 26 2001