A057165 Indices of addition steps in Recamán's sequence A005132.

0, 1, 2, 3, 5, 6, 7, 9, 11, 13, 15, 17, 18, 19, 21, 24, 26, 28, 30, 32, 33, 34, 36, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 66, 67, 69, 71, 73, 75, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 101, 102, 104, 106, 108, 112, 113, 114

Offset: 1

Author

N. J. A. Sloane, Sep 14 2000

Keywords

• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10001
• Nick Hobson, Python program for this sequence
• C. L. Mallows, Plot (jpeg) of first 10000 terms of A005132
• C. L. Mallows, Plot (postscript) of first 10000 terms of A005132
• Index entries for sequences related to Recamán's sequence

Crossrefs

Cf. A005132, A057166, A057167.

Union of A187921 and A187922.

Programs

Haskell

import Data.Set (Set, singleton, notMember, insert)
a057165 n = a057165_list !! n
a057165_list = r (singleton 0) 1 0 where
   r :: Set Integer -> Integer -> Integer -> [Integer]
   r s n x = if x > n && (x - n) `notMember` s
                then r (insert (x-n) s) (n+1) (x-n)
                else n : r (insert (x+n) s) (n+1) (x+n)
-- Reinhard Zumkeller, Mar 17 2011

Extensions

Initial zero added by N. J. A. Sloane, May 01 2020