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 A056775 #13 Mar 01 2020 04:41:33 %S A056775 5,7,11,17,19,29,31,41,45,47,59,61,65,67,71,80,89,97,99,101,112,117, %T A056775 127,135,137,139,151,167,171,176,179,181,196,199,207,209,211,227,229, %U A056775 239,251,257,269,271,272,279,281,294,304,310,312,337,347,367,369,389 %N A056775 Numbers k such that phi(k+12) = phi(k) + 12. %C A056775 Prime solutions are in A046133, common with primes in A015917. %H A056775 Amiram Eldar, <a href="/A056775/b056775.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Harvey P. Dale) %e A056775 65 is a term since phi(65) = 48, phi(65+12) = phi(77) = 60 = 48 + 12. %t A056775 Select[Range[400],EulerPhi[#]+12==EulerPhi[#+12]&] (* _Harvey P. Dale_, Jan 21 2013 *) %Y A056775 Cf. A000010, A001838, A015917, A054902, A046133, A046133. %K A056775 nonn %O A056775 1,1 %A A056775 _Labos Elemer_, Aug 17 2000