A035069 a(n) is root of square starting with digit 2: first term of runs.

5, 15, 45, 142, 448, 1415, 4473, 14143, 44722, 141422, 447214, 1414214, 4472136, 14142136, 44721360, 141421357, 447213596, 1414213563, 4472135955, 14142135624, 44721359550, 141421356238, 447213595500, 1414213562374

Offset: 1

Author

Patrick De Geest, Nov 15 1998

Keywords

• nonn
• base

Crossrefs

Cf. A067472 (squares), A035076 (2..9).

Programs

Mathematica

Table[Ceiling @ Sqrt[2 * 10^n], {n, 1, 24}] (* Amiram Eldar, Oct 08 2019 *)

Formula

a(n) = ceiling(sqrt(2*10^n)).

Extensions

Offset 1 from Michel Marcus, Oct 08 2019