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