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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 (list; graph; refs; listen; history; text; internal format)
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 Pascal’s triangle modulo 2, Congressus Numerantium, 200, pp. 35-52, 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

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Last modified December 8 17:11 EST 2016. Contains 278946 sequences.