OFFSET
1,1
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..300
Erich Friedman, Puzzles of the Week [N. J. A. Sloane, Mar 12 2011]
FORMULA
a(n) = A116501(n)^2.
EXAMPLE
309097^2 = a(3) = 9[5540]9[5540]9.
MATHEMATICA
w={}; Do[s = Reduce[(1 + 10^(1+e) + 100^(1+e)) d + 10 (1+10^(1+e)) x == y^2 && 0 <= x < 10^e && y>0, {x, y}, Integers]; If[s =!= False, w = Union[w, y^2 /. List@ ToRules@ s]], {e, 12}, {d, 9}]; w (* Giovanni Resta, Aug 01 2018 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Giovanni Resta, Feb 18 2006
EXTENSIONS
a(11)-a(13) from Giovanni Resta, Aug 01 2018
STATUS
approved