# [seqfan] Re: 8 seq. [from digits d<e<f to d>=e>=f]

Eric Angelini Eric.Angelini at kntv.be
Tue Oct 8 16:09:14 CEST 2013

```Hello Seqfans,
Lars Blomberg has extended the idea and computed
25 sequences. Some of them might be of interest
for the OEIS, I think. Many thanks to Lars!
Best,
É.

-----Message d'origine-----
De : SeqFan [mailto:seqfan-bounces at list.seqfan.eu] De la part de Eric Angelini
Envoyé : samedi 28 septembre 2013 23:03
À : Sequence Fanatics Discussion list
Objet : [seqfan] 8 seq. [from digits d<e<f to d>=e>=f]

Hello SeqFans,
We want a seq. S of terms a(n) such that:
1) a(1)=1
2) any three consecutive digits d, e and f of S don't show d<e<f
3) S is extended with the smallest integer not yet present in S.

I guess S starts like this:

S=1,2,10,3,11,4,12,13,14,15,5,6,16,17,7,8,18,19,20,
21-->120,200,201,121,122,130,202,131,132,133,140,
203,141,142,143,144,150,204,151,152,153,154,155,
160,205,...

[21-->120, above, meaning "all integers from 21 to 120"]

Playing with the signs <,=,> to be put between d, e and f,
one could compute the sequences T to Z with:
T ... d<=e<f
U ... d<e<=f
V ... d<=e<=f
W ... d>e>f
X ... d>=e>f
Y ... d>e>=f
Z ... d>=e>=f

Best,
É.

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