A127367 Inverse permutation to A127366.

0, 2, 1, 5, 3, 7, 4, 10, 6, 12, 8, 14, 9, 17, 11, 19, 13, 21, 15, 23, 16, 26, 18, 28, 20, 30, 22, 32, 24, 34, 25, 37, 27, 39, 29, 41, 31, 43, 33, 45, 35, 47, 36, 50, 38, 52, 40, 54, 42, 56, 44, 58, 46, 60, 48, 62, 49, 65, 51, 67, 53, 69, 55, 71, 57, 73, 59, 75, 61, 77, 63, 79, 64

Offset: 0

Author

Franklin T. Adams-Watters, Jan 11 2007

Keywords

• nonn

Comments

Let m be the largest number such that n >= m(m+1). If n is even, a(n) = n - m; otherwise a(n) = n + m + 1.

a(A005408(n)) > 0; a(A005843(n)) <= 0. [Reinhard Zumkeller, Oct 12 2011]

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..10000
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A127366, A002378, A000194.

Cf. A002378 (oblong numbers).

Programs

Haskell

a127367 n | even n    = n - m + 1
          | otherwise = n + m
          where m = length $ takeWhile (<= n) a002378_list
-- Reinhard Zumkeller, Oct 12 2011