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 A056776 #9 Mar 01 2020 04:44:08 %S A056776 45,65,80,99,112,117,135,171,176,196,207,209,272,279,294,304,310,312, %T A056776 369,406,429,477,496,531,592,656,657,711,752,801,909,927,944,981,1014, %U A056776 1072,1078,1179,1251,1359,1424,1557,1611,1629,1712,1719,1744,1786,1791 %N A056776 Composite numbers k such that phi(k+12) = phi(k) + 12. %C A056776 There are common cases with A054902. %H A056776 Amiram Eldar, <a href="/A056776/b056776.txt">Table of n, a(n) for n = 1..10000</a> %e A056776 656 is a term since it is composite and phi(656) = 320, phi(656+12) = phi(668) = 332 = 320 + 12. %e A056776 657 is a term since it is composite and phi(657) = 432, phi(657+12) = phi(669) = 444 = 432 + 12. %t A056776 Select[Range[1800], CompositeQ[#] && EulerPhi[# + 12] == EulerPhi[#] + 12 &] (* _Amiram Eldar_, Mar 01 2020 *) %Y A056776 Cf. A000010, A001838, A015917, A054902, A046133, A046133. %K A056776 nonn %O A056776 1,1 %A A056776 _Labos Elemer_, Aug 17 2000