cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A206579 Numbers k such that the periodic part of the continued fraction of sqrt(k) has more ones than any smaller k.

Original entry on oeis.org

2, 3, 7, 13, 43, 94, 133, 211, 244, 478, 604, 886, 1279, 1516, 1726, 3004, 3271, 3436, 4111, 4846, 4999, 6484, 6694, 7606, 9739, 10399, 10774, 12919, 13126, 15031, 16699, 17599, 17614, 18379, 19231, 25516, 25939, 32839, 32971, 39526, 40639, 42046, 42571
Offset: 1

Views

Author

T. D. Noe, Feb 29 2012

Keywords

Comments

The number 1 is the most common number in continued fractions of sqrt(k) for k = 1, 2, 3, ....
Most of the terms in this sequence are the product of a prime and a power of 2. There are only three exceptions less than 10^6: 133, 253621, and 375181.

Examples

			The periodic part of the continued fraction of sqrt(7) is (1, 1, 1, 4), which has more ones than any smaller square root.
		

Crossrefs

Cf. A206578 (least number having exactly n ones in its continued fraction).
Cf. A206580 (number of ones for a(n)).

Programs

  • Mathematica
    t = {{2, 0}}; Do[If[! IntegerQ[Sqrt[k]], cnt = Count[ContinuedFraction[Sqrt[k]][[2]], 1]; If[cnt > t[[-1, 2]], AppendTo[t, {k, cnt}]]], {k, 3, 50000}]; Transpose[t][[1]]