Numbers n such that phi(n) = (phi(n+1) + phi(n-1))/2.

Terms

a(0) =5187a(1) =5313a(2) =273525a(3) =292005a(4) =494715a(5) =536055a(6) =657855a(7) =2379975a(8) =3045075a(9) =9960045a(10) =15091545a(11) =19420665a(12) =23977305a(13) =28292745a(14) =45864225a(15) =62361495a(16) =81758325a(17) =93794715a(18) =213205575a(19) =309227655a(20) =602444325a(21) =806687427a(22) =1375738845a(23) =1411639047a(24) =1538174925a(25) =1589814975a(26) =1628145057