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 A078776 #20 Nov 25 2019 03:29:01 %S A078776 106,166,316,526,586,736,1156,1366,1485,1486,1576,1756,1786,1816,1996, %T A078776 2146,2206,2416,2476,2535,2536,2806,2836,3003,3004,3046,3316,3466, %U A078776 3675,3676,3886,3927,3928,4096,4126,4306,4455,4456,4485,4486,4516,4726,4785,4786 %N A078776 Numbers k such that phi(k-1) < phi(k) < phi(k+1), where phi is the Euler totient function (A000010). %D A078776 Jean-Marie De Koninck, Those Fascinating Numbers, American Mathematical Society, 2009, page 34, entry 105. %H A078776 Amiram Eldar, <a href="/A078776/b078776.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Harvey P. Dale) %e A078776 phi(105)=48 < phi(106)=52 < phi(107)=106, so 106 is in the sequence. %t A078776 Flatten[Position[Partition[EulerPhi[Range[5000]],3,1],_?(Min[Differences[ #]]> 0&)]//Quiet]+1 (* _Harvey P. Dale_, Jun 14 2019 *) %o A078776 (PARI) for (n=2,3000, if (eulerphi(n-1)<eulerphi(n) && eulerphi(n)<eulerphi(n+1),print1(n","))) %Y A078776 Cf. A000010. %K A078776 nonn %O A078776 1,1 %A A078776 _Jon Perry_, Jan 09 2003 %E A078776 More terms from _Michel Marcus_, Mar 17 2014