A000319 a(n) = floor(b(n)), where b(n) = tan(b(n-1)), b(0)=1.

1, 1, 74, -1, -2, -3, 0, 1, 30, -2, -2, 29, 1, 4, -6, 0, 1, 2, -1, -1, -1, -1, -2, -9, 0, 0, 1, 2, -2, -35, -1, -1, -1, -1, -1, -1, -1, -2, -3, 0, 0, 1, 5, -2, -2, 3, 1, 1, -4, -1, -1, -1, -1, -1, -1, -1, -1, -2, -3, 1, 2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -3, 0, 1, 2, -1, -2, -21, -7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset

0,3

Comments

Using 3000-digit precision, interval arithmetic provides an efficient method of computing over 2000000 terms of this sequence. The iteration is stopped when an interval contains an integer. So far, no term equals 319. - T. D. Noe, Mar 07 2008

Links

T. D. Noe, Table of n, a(n) for n = 0..10000

Example

From José María Grau Ribas, Apr 13 2010: (Start)
tan(tan(tan(1))) = -0.8635..., so a(3)=-1;
tan(tan(1)) = 74.68..., so a(2)=74. (End)

Mathematica

Floor[Table[Nest[Tan, 1, n], {n, 1, 200}]] (* José María Grau Ribas, Apr 13 2010 *)

Crossrefs

Sequence in context: A291992 A076848 A289853 * A033394 A114969 A104421

Adjacent sequences: A000316 A000317 A000318 * A000320 A000321 A000322

Keyword

sign

Author

N. J. A. Sloane

Status

approved