A131667 List of triples 2n, 1-2n, 0, n >= 1.

2, -1, 0, 4, -3, 0, 6, -5, 0, 8, -7, 0, 10, -9, 0, 12, -11, 0, 14, -13, 0, 16, -15, 0, 18, -17, 0, 20, -19, 0, 22, -21, 0, 24, -23, 0, 26, -25, 0, 28, -27, 0, 30, -29, 0, 32, -31, 0, 34, -33, 0, 36, -35, 0, 38, -37, 0, 40, -39, 0, 42, -41, 0, 44, -43, 0, 46, -45, 0, 48, -47, 0, 50, -49, 0

Offset

1,1

Links

Table of n, a(n) for n=1..75.

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

Formula

a(n) = sin(n*Pi/3)*((8n+6)*sin(n*Pi/3)-5*sqrt(3)*cos(n*Pi))*(-1)^floor(2n/3)/9. - Wesley Ivan Hurt, Sep 24 2017

From Chai Wah Wu, Feb 03 2021: (Start)

a(n) = - a(n-1) - a(n-2) + a(n-3) + a(n-4) + a(n-5) for n > 5.

G.f.: x*(-x^3 - x^2 - x - 2)/((x - 1)*(x^2 + x + 1)^2). (End)

Crossrefs

Sequence in context: A194734 A255528 A201701 * A322080 A361958 A334122

Adjacent sequences: A131664 A131665 A131666 * A131668 A131669 A131670

Keyword

sign,easy

Author

Paul Curtz, Sep 14 2007

Status

approved