A081828 Numbers n such that 2 successive terms of Hofstadter Q-sequence are the same.

1, 4, 7, 9, 10, 12, 13, 18, 20, 21, 22, 25, 27, 28, 29, 32, 41, 43, 44, 45, 46, 54, 59, 60, 61, 82, 87, 90, 91, 92, 93, 94, 102, 111, 133, 154, 157, 163, 177, 182, 186, 187, 188, 189, 190, 273, 334, 342, 350, 360, 367, 378, 379, 380, 381, 382, 418, 431, 441, 464, 483

Offset: 1

Author

Benoit Cloitre, Apr 10 2003

Keywords

• nonn

Comments

A005185(a(n)+1) = A005185(a(n)); A081827(a(n)) = 0.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..250
• Eric Weisstein's World of Mathematics, Hofstadter's Q-Sequence
• Wikipedia, Hofstadter sequence
• Index entries for Hofstadter-type sequences

Crossrefs

Cf. A081829, A081830, A194626.

Programs

Haskell

import Data.List (elemIndices)
a081828 n = a081828_list !! (n-1)
a081828_list = map (+ 1) $ elemIndices 0 a081827_list
-- Reinhard Zumkeller, Sep 15 2011