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 A081518 #10 May 21 2015 14:45:24
%S A081518 1,2,6,6,20,8,42,14,24,15,110,16,156,22,30,30,272,26,342,32,48,38,506,
%T A081518 34,120,46,78,48,812,39,930,62,81,62,110,52,1332,70,99,65,1640,57,
%U A081518 1806,78,95,86,2162,70,336,82,135,94,2756,80,198,96,152,110,3422,81,3660,118
%N A081518 Final term in row n of A081520.
%C A081518 a(p) = p(p-1) if p is a prime.
%C A081518 a(p^k) = p (p^k - 1) if p is a prime and k >= 1. - _Robert Israel_, May 21 2015
%H A081518 Ivan Neretin, <a href="/A081518/b081518.txt">Table of n, a(n) for n = 1..1000</a>
%p A081518 A:= n -> select(t->igcd(t,n)>1,[$1..n^2])[n-1]:
%p A081518 1, seq(A(n),n=2..100); # _Robert Israel_, May 21 2015
%t A081518 Table[Join[{1}, Select[Range[n^2], GCD[n, #] > 1 &, n - 1]][[-1]], {n, 1, 60}](* _Ivan Neretin_, May 21 2015 *)
%Y A081518 Cf. A081519, A081520.
%K A081518 nonn
%O A081518 1,2
%A A081518 _Amarnath Murthy_, Mar 27 2003
%E A081518 More terms from _Ryan Propper_, Nov 05 2005