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 A205565 Number of ways of writing n = u + v with u <= v, and u,v having in ternary representation no 3. 2

%I #9 Jul 13 2013 12:04:21

%S 1,1,1,1,2,1,1,1,1,1,2,1,2,4,2,1,2,1,1,1,1,1,2,1,1,1,1,1,2,1,2,4,2,1,

%T 2,1,2,4,2,4,8,4,2,4,2,1,2,1,2,4,2,1,2,1,1,1,1,1,2,1,1,1,1,1,2,1,2,4,

%U 2,1,2,1,1,1,1,1,2,1,1,1,1,1,2,1,2,4

%N Number of ways of writing n = u + v with u <= v, and u,v having in ternary representation no 3.

%H Reinhard Zumkeller, <a href="/A205565/b205565.txt">Table of n, a(n) for n = 0..10000</a>

%e a(30) = #{0+30, 3+27} = 2;

%e a(31) = #{0+31, 1+30, 3+28, 4+27} = 4;

%e a(32) = #{1+31, 4+28} = 2;

%e a(33) = #{3+30} = 1;

%e a(34) = #{3+31, 4+30} = 2;

%e a(35) = #{4+31} = 1;

%e a(36) = #{0+36, 9+27} = 2;

%e a(37) = #{0+37, 1+36, 9+28, 10+27} = 4;

%e a(38) = #{1+37, 10+28} = 2;

%e a(39) = #{0+39, 3+36, 9+30, 12+27} = 4;

%e a(40) = #{0+40, 1+39, 3+37, 4+36, 9+31, 10+30, 12+28, 13+27} = 8.

%o a205565 n = sum \$ map (a039966 . (n -)) \$

%o takeWhile (<= n `div` 2) a005836_list

%Y Cf. A039966, A005836, A120880.

%K nonn

%O 0,5

%A _Reinhard Zumkeller_, Jan 28 2012

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Last modified May 17 19:53 EDT 2024. Contains 372607 sequences. (Running on oeis4.)