A031600 Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 12.

1049, 3217, 3445, 5021, 6569, 8506, 8689, 11314, 11738, 11953, 14285, 16825, 17341, 18397, 20129, 20693, 21554, 22138, 22433, 22826, 23729, 24034, 24341, 24961, 25274, 25589, 26546, 29629, 30313, 31817, 33965, 35437, 35930, 36682, 37061, 38210

Offset

1,1

Links

Table of n, a(n) for n=1..36.

Example

CF(sqrt(145)) = (12, (24)), therefore 145 is not in the sequence.
CF(sqrt(1049)) = (32, (2,1,1,2,1,4,3,1,5,7,1,12, 12,1,7,5,1,3,4,1,2,1,1,2, 64)), therefore 1049 is in the sequence.

Crossrefs

Sequence in context: A337960 A331346 A164771 * A251272 A030083 A184203

Adjacent sequences: A031597 A031598 A031599 * A031601 A031602 A031603

Keyword

nonn

Author

David W. Wilson

Extensions

First term 145 removed by Georg Fischer, Jun 15 2019

Definition clarified by N. J. A. Sloane, Aug 18 2021

Status

approved