Ulam numbers n such that 3*n is also an Ulam number.

Terms

a(0) =1a(1) =2a(2) =6a(3) =16a(4) =38a(5) =138a(6) =182a(7) =209a(8) =309a(9) =341a(10) =612a(11) =1030a(12) =1389a(13) =2513a(14) =2584a(15) =2628a(16) =2650a(17) =2750a(18) =3031a(19) =3207a(20) =3290a(21) =3593a(22) =3742a(23) =3874a(24) =3962a(25) =4121a(26) =4155a(27) =4998a(28) =5384a(29) =5797