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 A070777 #20 Jul 08 2018 19:57:16
%S A070777 1,1,2,1,4,2,6,1,2,4,10,2,12,6,4,1,16,2,18,4,6,10,22,2,4,12,2,6,28,4,
%T A070777 30,1,10,16,6,2,36,18,12,4,40,6,42,10,4,22,46,2,6,4,16,12,52,2,10,6,
%U A070777 18,28,58,4,60,30,6,1,12,10,66,16,22,6,70,2,72,36,4,18,10,12,78,4,2,40,82,6
%N A070777 a(1) = 1; a(n) = (largest prime factor of n) - 1.
%C A070777 Also a(n) = Euler Phi of largest prime factor of n (previous name).
%C A070777 a(m*n) = max(a(m), a(n)). - _Robert Israel_, May 19 2015
%F A070777 a(n) = A000010(A006530(n)) = A006530(n) - 1 if n >= 2.
%e A070777 102 = 2*3*17, so a(102) = 17 - 1 = 16.
%p A070777 with(numtheory): A070777 := n -> `if`(n=1,1,phi(max(op(factorset(n))))): # _Peter Luschny_, Oct 23 2010
%t A070777 a[n_] := EulerPhi[Last[FactorInteger[n]][[1]]]; Table[a[n], {n, 1, 200}] (* _José María Grau Ribas_, Feb 21 2010 *)
%o A070777 (PARI) a(n) = if (n==1, 1, vecmax(factor(n)[,1]) - 1); \\ after A006530; _Michel Marcus_, May 19 2015
%Y A070777 Cf. A000010, A006530, A068211, A070812.
%K A070777 easy,nonn
%O A070777 1,3
%A A070777 _Labos Elemer_, May 07 2002
%E A070777 New name from _Michel Marcus_, May 19 2015