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A031421
Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted then there are 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
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
Subsequence of A003814.
Sequence in context: A256709 A110025 A059763 * A255183 A126438 A126582
KEYWORD
nonn
EXTENSIONS
a(1) corrected by T. D. Noe, Apr 04 2014
Data adapted to new definition by Georg Fischer, Jun 23 2019
STATUS
approved