A065005 Integers for which the periodic part of the continued fraction for the square root of n begins with 2.

2, 6, 12, 19, 20, 29, 30, 41, 42, 54, 55, 56, 70, 71, 72, 88, 89, 90, 107, 108, 109, 110, 129, 130, 131, 132, 153, 154, 155, 156, 178, 179, 180, 181, 182, 206, 207, 208, 209, 210, 236, 237, 238, 239, 240, 267, 268, 269, 270, 271, 272, 301, 302, 303, 304, 305

Offset: 1

Author

Robert G. Wilson v, Nov 01 2001

Keywords

• easy
• nonn

Examples

			The continued fraction for the square root of 12 is 3, {2, 6}.
		

Programs

Mathematica

Select[ Range[500], First[ Last[ ContinuedFraction[ Sqrt[ # ]]]] == 2 & ]