A067479 Smallest n-digit square starting with 9, or 0 if no such number exists.
9, 0, 900, 9025, 90000, 900601, 9000000, 90003169, 900000000, 9000127161, 90000000000, 900001331856, 9000000000000, 90000000369889, 900000000000000, 9000000036988900, 90000000000000000, 900000001801523401
Offset: 1
Crossrefs
Programs
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PARI
a(n) = if (n==2, 0, (sqrtint(9*10^(n-1)) + (n-1) % 2)^2); \\ Michel Marcus, Mar 23 2021
Formula
a(n+1) = (floor(sqrt(9*10^n)) + (n mod 2))^2, a(2)=0. - Sascha Kurz, Mar 18 2002
a(2k+1) = 9 * 10^(2k) for k >= 0. - Bernard Schott, Mar 23 2021
Extensions
More terms from Sascha Kurz, Mar 18 2002