Left-truncatable happy numbers: every suffix is a happy number and no digits are zero.

Terms

a(0) =1a(1) =7a(2) =31a(3) =91a(4) =97a(5) =291a(6) =331a(7) =391a(8) =397a(9) =931a(10) =2331a(11) =3331a(12) =3391a(13) =3931a(14) =5331a(15) =7331a(16) =7397a(17) =8397a(18) =9291a(19) =9331a(20) =23331a(21) =27397a(22) =32331a(23) =33391a(24) =33931a(25) =39291a(26) =39331a(27) =43331a(28) =48397a(29) =59291