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 A167768 #29 Jul 19 2017 08:53:10 %S A167768 1,7,31,32,2694,131071,50802031105 %N A167768 First of 4 or more consecutive integers with equal values of phi(phi(n)). %C A167768 Next term > 1266046940 (last term of A167767 b-file). - _Michel Marcus_, Jun 23 2013 %C A167768 No other terms < 1.32*10^12. - _Jud McCranie_, Jul 19 2017 %e A167768 p2(1) = p2(2) = p2(3) = p2(4) = 1, p2(7) = p2(8) = p2(9) = p2(10) = 2. %t A167768 a[n_] := EulerPhi[EulerPhi[n]]; Select[Range[10000], a[#] == a[# + 1] && a[# + 1] == a[# + 2] && a[# + 2] == a[# + 3] &] (* _G. C. Greubel_, Jun 23 2016 *) %o A167768 (PARI) pp(n) = eulerphi(eulerphi(n)) %o A167768 isA167768(n) = pp(n)==pp(n+1) && pp(n+1)==pp(n+2) && pp(n+2)==pp(n+3) \\ _Michael B. Porter_, Nov 24 2009 %Y A167768 Cf. A167767 (of which this list is a subset), A167766. %K A167768 more,nonn,hard %O A167768 1,2 %A A167768 _Fred Schneider_, Nov 11 2009 %E A167768 Edited by _N. J. A. Sloane_, Nov 12 2009 %E A167768 a(7) added by _Jud McCranie_, Jul 17 2017