[seqfan] Re: a(n+1) is the multiple of at least one digit of a(n)
Maximilian Hasler
maximilian.hasler at gmail.com
Tue May 28 23:47:45 CEST 2013
>
>
> a(n+1) is the smallest integer not yet in the sequence such that
> a(n+1) is the multiple of at least one digit of a(n):
>
> S=1,2,4,8,16,3,6,12,5,10,7,14,9,18,11,13,15,17,19,20,22,24,...
>
>
More terms:
1,2,4,8,16,3,6,12,5,10,7,14,9,18,11,13,15,17,19,20,22,24,26,28,30,21,23,27,32,33,36,39,42,34,40,44,48,52,25,35,45,50,55,60,54,56,65,
66,72,38,51,29,46,64,68,78,49,63,57,70,77,84,76,90,81,31,37,69,96,99,108,41,43,75,80,88,104,47,91,53,85,95,100,58,105,59,110,61,62,74,92,82,86,102,67,98,112,71,73,
PARI code : see https://oeis.org/draft/A218468
The least numbers not among a(1..1000) are
899, 901, 907, 911, 913, 919, 923, 929, 937, 941, 943, 947, 949, 953, 961,
967, 971, 977, 979, 983, 989, 991, 997,...
One sees that these are frequently prime.
Maximilian
[22 is in S because 22 is 11 times 2 -- this 2 being a digit of
> 20; 22 is the smallest available integer because 21 is neither
> a multiple of 2 or a multiple of 0]
>
> Best,
> É.
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