[seqfan] Re: Help for knives (and huge computer time)!

[Hans Havermann]

After 14, 18, 34, 38, 54, 58, comes 74, 78, 94, 98, ... I wish now I hadn't trashed my notebook because my approach to programming the sequence was to first eliminate all those numbers that weren't about to show up. The non-entries are simply built on divisibility: A multiple of 4 or 8 ending in 4 or 8 (respectively) is always preceded by an even digit. One can eliminate not only these 10 numbers but any larger numbers containing their digits-string as a substring. Once one has done that one can move to three-digit divisibility criteria. If I remember correctly I had 58 possible 3-digit substrings (after numbers containing 0, 14, 18, 34, 38, 54, 58, 74, 78, 94, 98 substrings were eliminated) that prevented numbers from belonging in the sequence.

On Jun 26, 2014, at 1:23 PM, Neil Sloane <njasloane at gmail.com> wrote:

> Giovanni, would it be possible to find more terms in the "excluded"
> sequence? In fact it should probably have an entry of its own - could you
> create it?