OFFSET
1,2
COMMENTS
No other terms below 10^41.
The sequence is probably finite.
The two distinct digits of a term cannot both be in the set {0,2,3,7,8}. Looking at the digits (with leading zeros) of i^2 mod 10^4 for 0 <= i < 10^4 shows that there are no repunit terms > 10 and the two distinct digits of a term must be one of the following 21 pairs: '01', '04', '09', '12', '14', '16', '18', '24', '25', '29', '34', '36', '45', '46', '47', '48', '49', '56', '67', '69', '89'. - Chai Wah Wu, Apr 06 2019
REFERENCES
Richard K. Guy, Unsolved Problems in Number Theory, Section F24 (at p. 262) (Springer-Verlag, 2d ed. 1994).
LINKS
Eric Weisstein's World of Mathematics, Square Number.
MATHEMATICA
Flatten[Table[Select[Flatten[Table[FromDigits/@Tuples[{a, b}, n], {n, 10}]], IntegerQ[ Sqrt[#]]&], {a, 9}, {b, 9}]]//Union (* Harvey P. Dale, Sep 21 2018 *)
CROSSREFS
KEYWORD
nonn,base,more,hard
AUTHOR
STATUS
approved