[seqfan] Re: Primitive version of A091784

Paolo Bonzini paolo.bonzini at gmail.com
Wed Aug 24 05:27:58 CEST 2016


If you define 2->36 as a primitive step, prepending 236 can be split in
prepending 1 and then doing the two steps 1->22->236.

Paolo

Il 23/ago/2016 17:56, "David Corneth" <davidacorneth at gmail.com> ha scritto:

> This can be pushed further.
> We start with no digits.
>
> Using the following operations:
> - prepend a 1, or 236.
> - replace a digit d by k digits d*k where d*k < 10 (if such k exists)
> - sort the digits
>
> All terms of A091784 can be found this way.
> An example:
> To find 23444688.
> We start with nothing.
> 1) Then, prepend 236. We get 236.
> 2) Prepend 1, we get 1236.
> 3) Replace a (the) digit 1 by 4 digits 1 * 4 = 4.
> We get: 4444236
> 4) Replace a digit 4 by 2 digits 2 * 4 = 8.
> We get (for example, which digit we pick doesn't matter)
> 44488236.
> 5) sort the digits.
> We get 23444688 as desired using 5 operations.
>
> This may lead to the following sequence:
> Number of operations required to find A091784(n).
>
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