A258203 Natural numbers n that have the property that starting from k = n, the fixed point of the map k -> floor(tan(k)) is strictly positive, and the smallest number encountered during the iteration is also strictly positive.

1, 4, 23, 26, 45, 48, 67, 70, 89, 92, 105, 111, 114, 127, 133, 136, 149, 155, 158, 171, 177, 180, 183, 193, 199, 202, 205, 215, 221, 224, 227, 243, 246, 249, 265, 268, 271, 290, 293, 300, 312, 315, 334, 337, 344, 356, 359, 378, 381, 400, 403, 422, 425, 444, 447, 460, 466, 469, 482, 488, 491, 504, 510, 513

Offset

1,2

Comments

Natural numbers n for which A258021(n) > 0 and A258201(n) > 0, or in other words, numbers n such that starting from k = n, the repeated application of map k -> floor(tan(k)) reaches 1 (or any other of strictly positive fixed points, whose existence however remains hypothetical) without ever visiting any negative number.

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

Prog

(Scheme, with Antti Karttunen's IntSeq-library)
(define A258203 (MATCHING-POS 1 1 (lambda (n) (and (> (A258021 n) 0) (> (A258201 n) 0)))))

Crossrefs

Complement of A258202 in A258024.

Cf. A258021, A258201.

Sequence in context: A115989 A016485 A258024 * A293698 A160613 A131545

Adjacent sequences: A258200 A258201 A258202 * A258204 A258205 A258206

Keyword

nonn

Author

Antti Karttunen & Daniel Forgues, May 26 2015

Status

approved