A067474 -id:A067474 - cp's OEIS frontend

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

Amarnath Murthy, Feb 09 2002

Cf. A000290, A035076 (roots), A045792.

Cf. 2: A067472, 3: A067473, 4: A067474, 5: A067475, 6: A067476, 7: A067477, 8: A067478.

a(n) = if (n==2, 0, (sqrtint(9*10^(n-1)) + (n-1) % 2)^2); \\ Michel Marcus, Mar 23 2021

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

More terms from Sascha Kurz, Mar 18 2002

A035071 a(n) = ceiling(sqrt(4*10^n)).

Original entry on oeis.org

2, 7, 20, 64, 200, 633, 2000, 6325, 20000, 63246, 200000, 632456, 2000000, 6324556, 20000000, 63245554, 200000000, 632455533, 2000000000, 6324555321, 20000000000, 63245553204, 200000000000, 632455532034, 2000000000000

Offset: 0

Patrick De Geest, Nov 15 1998

Previous name: "a(n) is root of square starting with digit 4: first term of runs."

Cf. A067474 (squares), A035076 (2..9).

Table[Ceiling @ Sqrt[4 * 10^n], {n, 0, 24}] (* Amiram Eldar, Oct 08 2019 *)

cp's OEIS Frontend

A067479 Smallest n-digit square starting with 9, or 0 if no such number exists.

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