

A094870


a(1)=1; for n>1 a(n) is the minimal positive integer t not equal to a(1), ..., a(n1) such that ta(ni) is not equal to a(ni)a(n2i) for all 1<=i<n/2.


10



1, 2, 4, 3, 5, 6, 8, 7, 10, 9, 13, 12, 14, 11, 17, 16, 22, 15, 23, 18, 21, 20, 25, 24, 26, 19, 28, 27, 29, 36, 32, 31, 33, 39, 38, 34, 41, 30, 37, 35, 44, 48, 42, 40, 43, 50, 46, 52, 47, 45, 54, 49, 56, 58, 57, 51, 61, 53, 59, 63, 60, 68, 64, 62, 70, 55, 65, 67, 73, 69, 83, 76
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OFFSET

1,2


COMMENTS

3n/8 <= a(n) < 3n/2 (P. Hegarty).
Conjecture: lim_{n>infinity} a(n)/n = 1 (P. Hegarty).
The Hegarty paper shows that this is a permutation.  Franklin T. AdamsWatters, May 26 2014


LINKS

Carl R. White, Table of n, a(n) for n = 1..10000
Peter Hegarty, Permutations avoiding arithmetic patterns, The Electronic Journal of Combinatorics, 11 (2004), #R39.
Index entries related to nonaveraging sequences


EXAMPLE

a(3)=4 because it can't be 1=a(1), 2=a(2) and 3=2*a(31)a(32).


MAPLE

A:=proc(n) option remember; local t, S, i; S:={$1..1000} minus {seq(A(i), i=1..n1)}; t:=min(S[]); i:=1; while i<floor((n+1)/2) do if tA(ni)=A(ni)A(n2*i) then S:=S minus {t}; t:=min(S[]); i:=1 else i:=i+1 fi od; t end: A(1):=1: seq(A(n), n=1..200);


CROSSREFS

Cf. A095689 (inverse permutation).
Sequence in context: A133256 A259570 A095690 * A075618 A095689 A083194
Adjacent sequences: A094867 A094868 A094869 * A094871 A094872 A094873


KEYWORD

easy,nonn


AUTHOR

Alec Mihailovs (alec(AT)mihailovs.com), Jun 16 2004


STATUS

approved



