login
A053887
Squares composed of digits {1,2,8}.
3
1, 81, 121, 8281, 11881, 128881, 11282881, 228281881, 1112822881, 111128222881, 11111282222881, 222128888112121, 228828882122281, 812121128112121, 1111112822222881, 8181222218111881, 111111128222222881, 11111111282222222881, 1111111112822222222881, 2118128181211211281281
OFFSET
1,2
COMMENTS
Includes all numbers of the form ((10^k-1)/3 + 26)^2 for k >= 3. - Andrew Howroyd, Sep 28 2024
FORMULA
a(n) = A053886(n)^2. - Andrew Howroyd, Oct 18 2024
MATHEMATICA
Table[Select[FromDigits/@Tuples[{1, 2, 8}, n], IntegerQ[Sqrt[#]]&], {n, 18}]//Flatten (* Harvey P. Dale, Jun 03 2022 *)
CROSSREFS
Cf. A053886.
Sequence in context: A280587 A273372 A366079 * A119943 A001245 A186463
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Mar 15 2000
STATUS
approved