A246404 Nonnegative integers k satisfying sec(k) < sec(k+1).

0, 2, 4, 6, 8, 10, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 121, 122, 124

Offset

1,2

Comments

A246404, A246405, and A246406 partition the nonnegative integers.

Links

Clark Kimberling, Table of n, a(n) for n = 1..1000

Mathematica

z = 500; f[x_] := f[x] = Sec[x];
Select[Range[0, z], f[#] < f[# + 1] &]  (* A246404 *)
Select[Range[0, z], f[#] > f[# + 1] < f[# + 2] &]  (* A246405 *)
Select[Range[0, z], f[#] > f[# + 1] > f[# + 2] < f[# + 3] &]  (* A246406 *)
Flatten[Position[Partition[Sec[Range[0, 150]], 2, 1], _?(#[[1]]<#[[2]]&), 1, Heads->False]]-1 (* Harvey P. Dale, May 09 2021 *)

Crossrefs

Cf. A246405, A246406, A246407 (complement of A246404).

Sequence in context: A187688 A334292 A085884 * A246408 A182766 A329828

Adjacent sequences: A246401 A246402 A246403 * A246405 A246406 A246407

Keyword

nonn,easy

Author

Clark Kimberling, Aug 25 2014

Status

approved