[seqfan] Quick and fun permutation
Eric Angelini
Eric.Angelini at kntv.be
Mon Sep 29 16:29:57 CEST 2014
Hello SeqFans,
Start S with a(1) = 1
Extend S with the smallest integer not yet present
whose leftmost digit divides a(n). I get (by hand,
in a couple of seconds):
S = 1,10,2,11,12,3,13,14,7,15,5,16,4,17,18,6,19,100,20,21,30,31,101,102,22,23,103,104,8,24,25,50,26,27,9,33,...
Example:
10 is the smallest available integer beginning with '1'
-- and this '1' is the only digit dividing a(1)
2 is the smallest available integer beginning with '2'
-- and this '2' divides a(2)
11 is the smallest available integer beginning with '1'
-- and this '1' is the only digit dividing a(3)
12 is the smallest available integer beginning with '1'
-- and this '1' divides a(4)
3 is the smallest available integer beginning with '3'
-- and this '3' divides a(5)
Every prime in S is followed by an integer starting with '1'.
S is a nice permutation of the integers > 0.
Best,
É.
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