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a(n) is root of square starting with digit 2: first term of runs.
3

%I #13 Oct 08 2019 15:49:17

%S 5,15,45,142,448,1415,4473,14143,44722,141422,447214,1414214,4472136,

%T 14142136,44721360,141421357,447213596,1414213563,4472135955,

%U 14142135624,44721359550,141421356238,447213595500,1414213562374

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

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

%t Table[Ceiling @ Sqrt[2 * 10^n], {n, 1, 24}] (* _Amiram Eldar_, Oct 08 2019 *)

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

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Nov 15 1998

%E Offset 1 from _Michel Marcus_, Oct 08 2019