

A163325


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


6



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

0,3


LINKS

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


FORMULA

a(0) = 0, a(n) = (n mod 3) + 3*A163325(floor(n/9))
a(n)=Sum_k>=0 {A030341(n,k)*b(k)} where b is the sequence (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

11 in ternary base (A007089) is written as '102' (1*9 + 0*3 + 2), from which we pick the "zeroth" and 2nd digits from the right, giving '12' = 1*3 + 2 = 5, thus a(11) = 5.


CROSSREFS

A059905 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: A055087 A025685 A194515 * A105186 A238406 A058709
Adjacent sequences: A163322 A163323 A163324 * A163326 A163327 A163328


KEYWORD

nonn,base


AUTHOR

Antti Karttunen, Jul 29 2009


EXTENSIONS

Edited by Charles R Greathouse IV, Nov 01 2009


STATUS

approved



