Right-truncatable happy numbers: every prefix is a happy number and no digits are zero.

Terms

a(0) =1a(1) =7a(2) =13a(3) =19a(4) =79a(5) =133a(6) =139a(7) =192a(8) =193a(9) =793a(10) =1332a(11) =1333a(12) =1335a(13) =1337a(14) =1339a(15) =1393a(16) =1929a(17) =1933a(18) =7937a(19) =7938a(20) =13323a(21) =13332a(22) =13334a(23) =13339a(24) =13393a(25) =13933a(26) =19293a(27) =19295a(28) =19296a(29) =19333