%I #23 Jul 24 2021 08:34:52
%S 35,65,77,161,185,209,221,335,341,371,377,437,485,515,611,671,707,731,
%T 767,779,851,899,917,965,1007,1067,1115,1157,1211,1247,1271,1337,1385,
%U 1397,1529,1535,1577,1631,1691,1781,1817,1841,1991,2117,2171,2201,2285,2291,2327
%N Composite numbers k such that psi(k - phi(k)) = phi(psi(k) - k).
%C 10217383 = 11*19^2*31*83 is the smallest term that is not squarefree.
%C A176875 is a subsequence.
%e 77 = 7*11 is a term because 77 - phi(77) = 17, psi(77) - 77 = 19 and phi(19) = psi(17).
%o (PARI) a001615(n) = my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1));
%o isok(n) = !isprime(n) && a001615(n-eulerphi(n))==eulerphi(a001615(n)-n); \\ after _Charles R Greathouse IV_ at A001615
%Y Cf. A000010, A001615, A176875, A290002.
%K nonn
%O 1,1
%A _Altug Alkan_, Sep 07 2017