A095689 Permutation of natural numbers, inverse permutation to A094870.

1, 2, 4, 3, 5, 6, 8, 7, 10, 9, 14, 12, 11, 13, 18, 16, 15, 20, 26, 22, 21, 17, 19, 24, 23, 25, 28, 27, 29, 38, 32, 31, 33, 36, 40, 30, 39, 35, 34, 44, 37, 43, 45, 41, 50, 47, 49, 42, 52, 46, 56, 48, 58, 51, 66, 53, 55, 54, 59, 61, 57, 64, 60, 63, 67, 78, 68, 62, 70, 65, 77, 75

Offset

1,2

Comments

2n/3 < a(n) <= 8n/3 (P. Hegarty).

Conjecture: lim_{n->infinity} a(n)/n = 1 (P. Hegarty).

Links

Carl R. White, Table of n, a(n) for n = 1..9660

Peter Hegarty, Permutations avoiding arithmetic patterns, The Electronic Journal of Combinatorics, 11 (2004), #R39.

Example

a(3)=4 because A094870(4)=3.

Maple

A:=proc(n) option remember; local t, S, i; S:={$1..300} minus {seq(A(i), i=1..n-1)}; t:=min(S[]); i:=1; while i<floor((n+1)/2) do if t-A(n-i)=A(n-i)-A(n-2*i) then S:=S minus {t}; t:=min(S[]); i:=1 else i:=i+1 fi od; t end: A(1):=1: L:=[seq(A(n), n=1..200)]: a:=n-> if member(n, L, 'p') then p else 0 fi: seq(a(n), n=1..194);

Crossrefs

Cf. A094870.

Sequence in context: A095690 A094870 A075618 * A083194 A105366 A077156

Adjacent sequences: A095686 A095687 A095688 * A095690 A095691 A095692

Keyword

easy,nonn

Author

Alec Mihailovs (alec(AT)mihailovs.com), Jul 05 2004

Status

approved