1,2

Write the natural numbers as a triangle:

1

2...3

4...5...6

7...8...9..10

11..12..13..14..15

Now read off the numbers diagonally from upper-right to lower-left. 1 -> 2 -> 3 -> 4 -> 5 -> 7 -> 6 -> 8 -> 11 -> 9 -> 12 -> ...

Ivan Neretin, Table of n, a(n) for n = 1..10000

Index entries for sequences that are permutations of the natural numbers

a(n) = A090894(n-1)+1. Cf. A092180.

Sequence in context: A293052 A273751 A056017 * A338698 A066937 A217266

Adjacent sequences: A091992 A091993 A091994 * A091996 A091997 A091998

easy,nonn

Felix Tubiana (fat2(AT)columbia.edu), Mar 17 2004

approved