A109682 Numbers missing from A109681.

2, 7, 24, 80, 238, 723, 2183, 5653, 19674, 59042, 177145, 531429, 1594313, 4782955, 14348892, 43046708, 129140146, 387420471, 1162261451, 3486784397, 10460353182, 31381059590, 94143178804, 282429536457, 847288609421

Offset: 1

Author

Philippe Deléham, Aug 08 2005

Keywords

• nonn

Comments

3^(n-1) < a(n) < 3^n. - Reinhard Zumkeller, Nov 19 2013

Crossrefs

Cf. A109681, A109683, also A109684 (ternary equivalents).

Programs

Haskell

-- import Data.List (delete)
a109682 n = a109682_list !! (n-1)
a109682_list = compl a109681_list [0..] where
   compl us'@(u:us) vs'@(v:vs)
       | u == v    = compl us vs
       | u > 3 * v = v : compl us (delete u vs)
       | otherwise = compl us (delete u vs')
-- Reinhard Zumkeller, Nov 19 2013