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

0,5

Links

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

Example

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.

Prog

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

Crossrefs

Cf. A039966, A005836, A120880.

Sequence in context: A184170 A025919 A095684 * A064531 A274468 A211993

Adjacent sequences: A205562 A205563 A205564 * A205566 A205567 A205568

Keyword

nonn

Author

Reinhard Zumkeller, Jan 28 2012

Status

approved