

A031421


Numbers n such that continued fraction for sqrt(n) has odd period and a pair of central terms both equal to 8.


1



509, 1450, 2237, 2425, 3946, 4778, 5189, 5473, 5618, 5914, 6445, 6761, 7417, 8185, 9178, 9938, 10133, 10426, 10529, 10826, 10933, 11441, 11861, 12074, 12289, 12506, 12829, 13273, 14653, 14765, 15241, 16217, 16586, 16837, 17090, 17989, 18385, 18650, 18778
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OFFSET

1,1


LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000 [shifted by Georg Fischer, Jun 23 2019]


MATHEMATICA

n = 1; t = {}; While[Length[t] < 50, n++; If[! IntegerQ[Sqrt[n]], c = ContinuedFraction[Sqrt[n]]; len = Length[c[[2]]]; If[OddQ[len] && c[[2, (len + 1)/2]] == 8 && c[[2, (len + 1)/2  1]] == 8, AppendTo[t, n]]]]; t (* T. D. Noe, Apr 04 2014; adapted by Georg Fischer, Jun 23 2019 *)


CROSSREFS

Cf. A031404A031423.
Sequence in context: A256709 A110025 A059763 * A255183 A126438 A126582
Adjacent sequences: A031418 A031419 A031420 * A031422 A031423 A031424


KEYWORD

nonn


AUTHOR

David W. Wilson


EXTENSIONS

a(1) corrected by T. D. Noe, Apr 04 2014
Data adapted to new definition by Georg Fischer, Jun 23 2019


STATUS

approved



