A020440 Period of continued fraction for sqrt(n) contains exactly four 1's.

13, 21, 31, 57, 61, 67, 73, 74, 92, 106, 108, 109, 111, 112, 116, 129, 137, 158, 161, 162, 183, 185, 193, 204, 207, 236, 237, 243, 246, 251, 261, 262, 265, 273, 274, 275, 282, 297, 298, 308, 314, 317, 329, 332, 341, 346, 351, 355, 364, 375, 381, 383, 384, 388, 406, 412

Offset

1,1

Links

Table of n, a(n) for n=1..56.

Mathematica

Select[ Range@ 1900, !IntegerQ[ Sqrt@ #] && Count[ ContinuedFraction[ Sqrt@ #][[2]], 1] == 4 &] (* Robert G. Wilson v, Jul 03 2011 *)

Crossrefs

Sequence in context: A331116 A050711 A282844 * A164458 A164452 A164444

Adjacent sequences: A020437 A020438 A020439 * A020441 A020442 A020443

Keyword

nonn

Author

David W. Wilson

Status

approved