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

Author

Wesley Ivan Hurt, Dec 22 2011

Keywords

• nonn
• easy

Comments

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

Links

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

Crossrefs

Cf. A000027.

Programs

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 *)

PARI

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

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