Valid groups of final digits a square number made entirely of the digits 6, 7 and 8 can have.

Terms

a(0) =6a(1) =76a(2) =676a(3) =776a(4) =876a(5) =6676a(6) =7776a(7) =7876a(8) =8676a(9) =67776a(10) =67876a(11) =68676a(12) =76676a(13) =77776a(14) =87776a(15) =87876a(16) =88676a(17) =667776a(18) =667876a(19) =668676a(20) =676676a(21) =677776a(22) =687876a(23) =688676a(24) =767876a(25) =768676a(26) =776676a(27) =787776a(28) =787876a(29) =788676