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 A081603 Number of 2's in ternary representation of n. 30
 0, 0, 1, 0, 0, 1, 1, 1, 2, 0, 0, 1, 0, 0, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 2, 3, 0, 0, 1, 0, 0, 1, 1, 1, 2, 0, 0, 1, 0, 0, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 2, 3, 1, 1, 2, 1, 1, 2, 2, 2, 3, 1, 1, 2, 1, 1, 2, 2, 2, 3, 2, 2, 3, 2, 2, 3, 3, 3, 4, 0, 0, 1, 0, 0, 1, 1, 1, 2, 0, 0, 1, 0, 0, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,9 COMMENTS A077267(n) + A062756(n) + a(n) = A081604(n); a(n) = (A053735(n) - A062756(n))/2. Fixed point of the morphism : 0 ->001 ; 1 ->112 ; 2 ->223 ; 3 ->334, etc , starting from a(0)=0. - Philippe Deléham, Oct 26 2011 LINKS R. Zumkeller, Table of n, a(n) for n = 0..10000 F. T. Adams-Waters, F. Ruskey, Generating Functions for the Digital Sum and Other Digit Counting Sequences, JIS 12 (2009) 09.5.6 Eric Weisstein's World of Mathematics, Ternary. FORMULA a(n) = if n<3 then [n/2] else a([n/3]) + [(n mod 3)/2]. MAPLE A081603 := proc(n)     local a, d ;     a := 0 ;     for d in convert(n, base, 3) do         if d= 2 then             a := a+1 ;         end if;     end do:     a; end proc: # R. J. Mathar, Jul 12 2016 MATHEMATICA Table[Count[IntegerDigits[n, 3], 2], {n, 0, 6!}] (* Vladimir Joseph Stephan Orlovsky, Jul 25 2009 *) Nest[ Flatten[# /. a_Integer -> {a, a, a + 1}] &, {0}, 5] (* Robert G. Wilson v, May 20 2014 *) DigitCount[Range[0, 120], 3, 2] (* Harvey P. Dale, Jul 10 2019 *) PROG (Haskell) a081603 0 = 0 a081603 n = a081603 n' + m `div` 2 where (n', m) = divMod n 3 -- Reinhard Zumkeller, Feb 21 2013 CROSSREFS Cf. A007089, A074940, A005836, A081610, A081611. Sequence in context: A147645 A091970 A093955 * A273513 A330005 A165277 Adjacent sequences:  A081600 A081601 A081602 * A081604 A081605 A081606 KEYWORD nonn,base AUTHOR Reinhard Zumkeller, Mar 23 2003 STATUS approved

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Last modified December 15 00:30 EST 2019. Contains 329988 sequences. (Running on oeis4.)