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

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, 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, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 4

Offset: 0

Author

Reinhard Zumkeller, Jan 28 2012

Keywords

• nonn

Examples

			a(30) = #{0+30, 3+27} = 2;
a(31) = #{0+31, 1+30, 3+28, 4+27} = 4;
a(32) = #{1+31, 4+28} = 2;
a(33) = #{3+30} = 1;
a(34) = #{3+31, 4+30} = 2;
a(35) = #{4+31} = 1;
a(36) = #{0+36, 9+27} = 2;
a(37) = #{0+37, 1+36, 9+28, 10+27} = 4;
a(38) = #{1+37, 10+28} = 2;
a(39) = #{0+39, 3+36, 9+30, 12+27} = 4;
a(40) = #{0+40, 1+39, 3+37, 4+36, 9+31, 10+30, 12+28, 13+27} = 8.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A039966, A005836, A120880.

Programs

Haskell

a205565 n = sum $ map (a039966 . (n -)) $
                  takeWhile (<= n `div` 2) a005836_list