

A163326


Pick digits at the odd distance from the least significant end of the ternary expansion of n, then convert back to decimal.


6



0, 0, 0, 1, 1, 1, 2, 2, 2, 0, 0, 0, 1, 1, 1, 2, 2, 2, 0, 0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 3, 3, 3, 4, 4, 4, 5, 5, 5, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 6, 6, 6, 7, 7, 7, 8, 8, 8, 6, 6, 6, 7, 7, 7, 8, 8, 8, 0, 0, 0, 1, 1, 1, 2, 2, 2, 0, 0, 0, 1, 1, 1, 2, 2, 2, 0, 0, 0
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OFFSET

0,7


LINKS

A. Karttunen, Table of n, a(n) for n = 0..728


FORMULA

a(n) = A163325(floor(n/3))
a(n)=Sum_k>=0 {A030341(n,k)*b(k)} with (b) = (0,1,0,3,0,9,0,27,0,81,0,243,0,...) : powers of 3 alternating with zeros.  From Philippe Deléham, Oct 22 2011.


EXAMPLE

42 in ternary base (A007089) is written as '1120' (1*27 + 1*9 + 2*3 + 0), from which we pick the first and 3rd digits from the right (zerobased!), giving '12' = 1*3 + 2 = 5, thus a(42) = 5.


CROSSREFS

A059906 is an analogous sequence for binary. Note that A037314(A163325(n)) + 3*A037314(A163326(n)) = n for all n. Cf. A007089, A163327A163329.
Sequence in context: A180834 A214458 A133873 * A028953 A037865 A039969
Adjacent sequences: A163323 A163324 A163325 * A163327 A163328 A163329


KEYWORD

nonn,base


AUTHOR

Antti Karttunen, Jul 29 2009


EXTENSIONS

Edited by Charles R Greathouse IV, Nov 01 2009


STATUS

approved



