A087055 Largest square number less than 2*n^2.

1, 4, 16, 25, 49, 64, 81, 121, 144, 196, 225, 256, 324, 361, 441, 484, 576, 625, 676, 784, 841, 961, 1024, 1089, 1225, 1296, 1444, 1521, 1681, 1764, 1849, 2025, 2116, 2304, 2401, 2500, 2704, 2809, 3025, 3136, 3249, 3481, 3600, 3844, 3969, 4225, 4356, 4489

Offset: 1

Author

Jens Voß, Aug 07 2003

Keywords

• easy
• nonn

Examples

			a(10) = 196 because 196 is the largest square less than 2*10^2 = 200.
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000290, A001951, A087056, A087057, A087058, A087059, A087060.

Programs

Mathematica

Table[Floor[Sqrt[2n^2-1]],{n,100}]^2  (* Harvey P. Dale, Mar 26 2011 *)

PARI

a(n) = sqrtint(2*n^2)^2; \\ Michel Marcus, Jul 08 2020

Formula

a(n) = A001951(n)^2 = floor(n*sqrt(2))^2.