OFFSET
1,2
COMMENTS
Includes all numbers of the forms (10^k + 9)^2, (9*10^k + 1)^2, (100^k + 4*10^k + 1)^2, and (10*100^k + 9*10^k + 1)^2 for k >= 2. - Andrew Howroyd, Oct 18 2024
LINKS
Zhao Hui Du, Table of n, a(n) for n = 1..91
Patrick De Geest, Index to related sequences
Hisanori Mishima, Sporadic tridigital solutions
FORMULA
a(n) = A058421(n)^2. - Andrew Howroyd, Oct 18 2024
MATHEMATICA
Select[FromDigits/@Tuples[{0, 1, 8}, 17], Mod[#, 10]!=0&&IntegerQ[Sqrt[#]]&] (* Harvey P. Dale, Sep 09 2022 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Nov 15 2000
STATUS
approved