A184985 Nonnegative integers excluding 2.

0, 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70

Offset

1,3

Comments

Number of adjacent pairs of sectors in a circle with n equal sections.

Links

Table of n, a(n) for n=1..70.

Index entries for linear recurrences with constant coefficients, signature (2,-1).

Formula

G.f.: (1+x-x^2)*x^2/(1-x)^2. - Philippe Deléham, Dec 23 2011

a(1) = 0, a(2) = 1, a(n) = n for n > 2. - Wesley Ivan Hurt, Jun 17 2019

Maple

A184985:=n->piecewise(n<3, n-1, n); seq(A184985(n), n=1..100);

Mathematica

CoefficientList[Series[(1+x-x^2)*x^2/(1-x)^2, {x, 0, 50}], x] (* G. C. Greubel, Jun 03 2017 *)
Range[0, 70]/.(2->Nothing) (* Harvey P. Dale, Jul 14 2026 *)
(* Alternative: *)
LinearRecurrence[{2, -1}, {0, 1, 3, 4}, 70] (* Harvey P. Dale, Jul 14 2026 *)

Prog

(PARI) a(n)=n-(n<3) \\ Charles R Greathouse IV, Dec 22 2011

Crossrefs

Cf. A000027.

Sequence in context: A030544 A141213 A171950 * A114637 A009056 A065475

Adjacent sequences: A184982 A184983 A184984 * A184986 A184987 A184988

Keyword

nonn,easy,changed

Author

Wesley Ivan Hurt, Dec 22 2011

Status

approved