A348485 - OEIS

%I #10 Oct 25 2021 11:05:53

%S 1,1,2,2,1,3,2,2,3,1,4,2,2,3,1,5,2,3,3,2,4,3,2,4,3,3,4,2,5,1,7,2,4,3,

%T 3,4,2,5,1,7,2,4,3,3,4,2,5,1,7,2,5,1,7,2,5,3,3,4,4,3,3,4,4,3,3,4,4,5,

%U 2,7,1,9,2,5,3,3,5,2,7,1,10,2,7,1,11,2

%N Lexicographically earliest sequence of positive integers in which, for all positive k, there are exactly k contiguous pairs whose product is k, and a(k) * a(k+1) <> a(k+1) * a(k+2).

%C This sequence is a variant of A307720 where we don't allow consecutive equal products of contiguous pairs.

%H Rémy Sigrist, <a href="/A348485/b348485.txt">Table of n, a(n) for n = 1..10000</a>

%H Rémy Sigrist, <a href="/A348485/a348485.gp.txt">PARI program for A348485</a>

%e The first terms, alongside a(n)*a(n+1), are:

%e   n   a(n)  a(n)*a(n+1)

%e   --  ----  -----------

%e    1     1            1

%e    2     1            2

%e    3     2            4

%e    4     2            2

%e    5     1            3

%e    6     3            6

%e    7     2            4

%e    8     2            6

%e    9     3            3

%e   10     1            4

%e   11     4            8

%e   12     2            4

%e   13     2            6

%e   14     3            3

%e   15     1            5

%o (PARI) See Links section.

%Y Cf. A307720, A348486 (the products).

%K nonn

%O 1,3

%A _Rémy Sigrist_, Oct 21 2021