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 A072612 #6 Mar 30 2012 18:39:04
%S A072612 0,1,0,0,1,0,0,0,1,2,1,0,0,0,0,1,1,0,1,0,1,2,1,0,1,2,1,0,1,0,0,0,1,2,
%T A072612 1,0,1,0,0,0,1,0,1,0,1,2,1,0,1,2,3,2,1,0,1,0,0,1,1,0,1,0,0,1,2,3,1,0,
%U A072612 1,2,1,0,1,0,1,2,1,0,1,0,1,2,1,0,1,2,3,2,1,0,0,1,0,1,1,0,1,0,1,2,1,0,1,0,1
%N A072612 Minimal value of { abs(n-sigma(k)) : k>0 }.
%C A072612 a(A002191(k)) = 0
%F A072612 Conjecture : S(n) = sum( k=1, n, a(k) ) = n + O(sqrt(n)) and more precisely for n large enough : n - (5/2)*sqrt(n) < S(n) < n - (3/2)*sqrt(n)
%o A072612 (PARI) a(n)=vecmin(vector(n,k,abs(n-sigma(k))))
%K A072612 easy,nonn
%O A072612 1,10
%A A072612 _Benoit Cloitre_, Aug 11 2002