

A061392


a(n) = a(floor[n/3]) + a(ceiling[n/3]) with a(0) = 0 and a(1) = 1.


6



0, 1, 1, 2, 2, 2, 2, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 10, 10, 10, 10, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 13, 13, 14, 14, 14, 14, 15, 15, 16, 16, 16, 16, 16, 16, 16
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OFFSET

0,4


COMMENTS

Number of nonnegative integers < n having no 1 in their ternary representation.  Reinhard Zumkeller, Mar 23 2003; corrected by Henry Bottomley, Mar 24 2003


LINKS

Table of n, a(n) for n=0..87.
Sam Northshield, Sums across Pascalâ€™s triangle modulo 2, Congressus Numerantium, 200, pp. 3552, 2010. [From Johannes W. Meijer, Jun 05 2011]


FORMULA

a(n+1) + A081609(n) = n+1.  Reinhard Zumkeller, Mar 23 2003; corrected by Henry Bottomley, Mar 24 2003
From Johannes W. Meijer, Jun 05 2011: (Start)
a(3*n+1) = a(n+1) + a(n), a(3*n+2) = a(n+1) + a(n) and a(3*n+3) = 2*a(n+1), for n>=1, with a(0)=0, a(1)=1, a(2)=1 and a(3)=2. (Northshield)
G.f.: x*prod((1+x^(3^n)+2*x^(2*3^n)+x^(3*3^n)+x^(4*3^n)), n>=0). (Northshield) (End)


MAPLE

A061392 := proc(n) option remember; local a : if n <=1 then n else A061392(floor(n/3)) + A061392(ceil(n/3)) fi: end: seq(A061392(n), n=0..87); # Johannes W. Meijer, Jun 05 2011


CROSSREFS

k appears A061393 times. Cf. A007089, A062756, A081608, A081609, A081611.
Sequence in context: A194292 A073578 A087866 * A048273 A175387 A024542
Adjacent sequences: A061389 A061390 A061391 * A061393 A061394 A061395


KEYWORD

nonn


AUTHOR

Henry Bottomley, Apr 30 2001


STATUS

approved



