A093390 a(n) = floor(n/9) + floor((n+1)/9) + floor((n+2)/9).

0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 3, 3, 3, 3, 3, 3, 4, 5, 6, 6, 6, 6, 6, 6, 6, 7, 8, 9, 9, 9, 9, 9, 9, 9, 10, 11, 12, 12, 12, 12, 12, 12, 12, 13, 14, 15, 15, 15, 15, 15, 15, 15, 16, 17, 18, 18, 18, 18, 18, 18, 18, 19, 20, 21, 21, 21, 21, 21, 21, 21, 22, 23, 24, 24, 24, 24, 24, 24, 24, 25

Offset: 0

Author

Reinhard Zumkeller, Mar 28 2004

Keywords

• nonn
• easy

Comments

Half the domination number of the camel's graph (from Tamerlane Chess) on a 2 X (n-6) chessboard. - David Nacin, May 28 2017

Links

• Michael De Vlieger, Table of n, a(n) for n = 0..10000
• Index entries for linear recurrences with constant coefficients, signature (2,-1,-1,2,-1,-1,2,-1)

Crossrefs

Cf. A004524, A093391, A093392, A093393, A287394.

Programs

Mathematica

Array[Total@ Map[Floor[#/9] &, # + Range[0, 2]] &, 80, 0] (* or *)
CoefficientList[Series[x^7/((x^6 + x^3 + 1) (x - 1)^2), {x, 0, 79}], x] (* Michael De Vlieger, Dec 12 2017 *)

PARI

a(n)=n\9+(n+1)\9+(n+2)\9 \\ Charles R Greathouse IV, Oct 16 2015

Formula

G.f.: x^7 / ( (x^6+x^3+1)*(x-1)^2 ). - R. J. Mathar, Mar 22 2011

a(n) = n/3 + O(1). - Charles R Greathouse IV, Oct 16 2015

a(n) = A287394(n-6)/2. - David Nacin, May 28 2017