

A093390


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


6



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
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OFFSET

0,9


COMMENTS

Half the domination number of the camel's graph (from Tamerlane Chess) on a 2 X (n6) 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)


FORMULA

G.f.: x^7 / ( (x^6+x^3+1)*(x1)^2 ).  R. J. Mathar, Mar 22 2011
a(n) = n/3 + O(1).  Charles R Greathouse IV, Oct 16 2015
a(n) = A287394(n6)/2.  David Nacin, May 28 2017


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 *)


PROG

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


CROSSREFS

Cf. A004524, A093391, A093392, A093393, A287394.
Sequence in context: A069637 A072292 A243282 * A025789 A080585 A295977
Adjacent sequences: A093387 A093388 A093389 * A093391 A093392 A093393


KEYWORD

nonn,easy


AUTHOR

Reinhard Zumkeller, Mar 28 2004


STATUS

approved



