A232244 A walk based on the digits of sqrt(2) (A002193).

1, 2, 3, 4, 3, 2, 1, 2, 3, 4, 3, 2, 1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 3, 4, 5, 6, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 8, 7, 6, 5, 4, 3, 2, 3, 4, 3

Offset: 1

Author

Philippe Deléham, Nov 20 2013 at the suggestion of N. J. A. Sloane

Keywords

• nonn
• easy
• base

Comments

sqrt(2)= 1. 41421354237...

Between 1 and 4 we place 2 and 3.

Between 4 and 1 we place 3 and 2.

Between 1 and 4 we place 2 and 3.

Between 4 and 2 we place 3 and so on.

This gives:

1, 2, 3, 4, 3, 2, 1, 2, 3, 4, 3, 2, 1, 2, 3, ...

This could be called a walk (or promenade) on the digits of sqrt(2).

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A002193.

Programs

Haskell

a232244 n = a232244_list !! (n-1)
a232244_list = 1 : concat (zipWith w a002193_list $ tail a002193_list)
   where w v u | v > u     = [v - 1, v - 2 .. u]
               | v < u     = [v + 1 .. u]
               | otherwise = [v]
-- Reinhard Zumkeller, Nov 22 2013