Numbers k for which phi(k) = phi(k+1) - phi(k-1).

Terms

a(0) =2a(1) =4a(2) =6a(3) =10a(4) =16a(5) =22a(6) =36a(7) =40a(8) =46a(9) =100a(10) =136a(11) =232a(12) =256a(13) =856a(14) =1036a(15) =1296a(16) =1540a(17) =1600a(18) =2016a(19) =4336a(20) =6526a(21) =9178a(22) =14400a(23) =16096a(24) =30496a(25) =55386a(26) =61132a(27) =62800a(28) =65536a(29) =72580