Numbers k such that k and k^2 use only the digits 5, 6, 7, 8 and 9.

Terms

a(0) =76a(1) =87a(2) =766a(3) =887a(4) =7666a(5) =8887a(6) =9786a(7) =76587a(8) =76666a(9) =87576a(10) =759576a(11) =766666a(12) =869866a(13) =869867a(14) =886886a(15) =888587a(16) =988866a(17) =7666666a(18) =8766867a(19) =8885887a(20) =76587576a(21) =76666666a(22) =76789686a(23) =86998666a(24) =87565786a(25) =87685676a(26) =88766867a(27) =97759786a(28) =97957576a(29) =766666666