A155449 Numbers k == 6 or 11 (mod 17).

6, 11, 23, 28, 40, 45, 57, 62, 74, 79, 91, 96, 108, 113, 125, 130, 142, 147, 159, 164, 176, 181, 193, 198, 210, 215, 227, 232, 244, 249, 261, 266, 278, 283, 295, 300, 312, 317, 329, 334, 346, 351, 363, 368, 380, 385, 397, 402, 414, 419, 431, 436, 448, 453

Offset

1,1

Comments

Or, numbers k such that k^2 == 2 (mod 17).

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (1,1,-1).

Formula

a(n) = a(n-1) + a(n-2) - a(n-3); a(1)=6, a(2)=11, a(3)=23.

G.f.: x*(6 + 5*x + 6*x^2)/((1 + x)*(1 - x)^2). - Vincenzo Librandi, May 03 2014

Sum_{n>=1} (-1)^(n+1)/a(n) = tan(5*Pi/34)*Pi/17. - Amiram Eldar, Feb 27 2023

Mathematica

LinearRecurrence[{1, 1, -1}, {6, 11, 23}, 100] (* Vincenzo Librandi, Feb 29 2012 *)
CoefficientList[Series[(6 + 5 x + 6 x^2)/((1 + x) (1 - x)^2), {x, 0, 60}], x] (* Vincenzo Librandi, May 03 2014 *)

Crossrefs

Sequence in context: A170880 A239767 A046616 * A220154 A362441 A309742

Adjacent sequences: A155446 A155447 A155448 * A155450 A155451 A155452

Keyword

nonn,easy

Author

Vincenzo Librandi, Jan 22 2009

Extensions

Simpler definition from Franklin T. Adams-Watters, Jun 16 2010

Status

approved