# [seqfan] Re: Extended with a pair of integers

Frank Adams-Watters franktaw at netscape.net
Sat Oct 11 20:10:04 CEST 2014

That should be 8,26, not 8,24.

The odd bifurcation of this sequence is A005228; and the other half is
in A030124.

-----Original Message-----
From: Eric Angelini <Eric.Angelini at kntv.be>
To: Sequence Discussion list <seqfan at list.seqfan.eu>
Sent: Sat, Oct 11, 2014 11:17 am
Subject: [seqfan] Extended with a pair of integers

Hello SeqFans,
S starts with 1 and is always extended with a pair of integers:
- the first integer of the pair is the smallest integer not already in
S;
- the second integer is the sum of the two integers that preceed it.

S=1
S=1,2,3,
S=1,2,3,4,7
S=1,2,3,4,7,5,12
S=1,2,3,4,7,5,12,6,18
S=1,2,3,4,7,5,12,6,18,8,24
S=1,2,3,4,7,5,12,6,18,8,24,9,33
S=1,2,3,4,7,5,12,6,18,8,24,9,33,10,43
etc.
S is a permutation of the intergers > 0
Every integer having an odd position in S
is the sum of the two integers before it
and the absolute difference of the two
integers after it (except for 1, the first term of S):
3, for instance, is 1+2 and also |4-7|
Best,
É.