[seqfan] Re: A019278 and A257670

[michel.marcus at free.fr]

Probably my code in A257670 is the culprit 

----- Mail original -----

De: "David Corneth" <davidacorneth at gmail.com> 
À: "Sequence Fanatics Discussion list" <seqfan at list.seqfan.eu> 
Envoyé: Mardi 19 Novembre 2019 19:08:23 
Objet: [seqfan] Re: A019278 and A257670 

What's long? 
[1, 2, 2, 2, 2, 16, 21, 2, 19, 2, 64, 43, 81, 2, 73, 29, 2, 33, 361, 81, 
361, 27, 189, 189, 1029, 189, 2133, 3137, 786, 1348, 189, 786, 6730, 28927, 
5, 10308, 57337, 12873, 786, 6730, 17593, 786, 343976, 28927, 291848, 
33412, 22521, 786, 21657, 185897, 43856, 937, 884709, 453, 97473, 386710, 
293957, 786, 277700, 54692, 4889, 461, 64479, 89949, 64851, 544047] 
Takes under a minute, 

[1, 2, 2, 2, 2, 16, 21, 2, 19, 2, 64, 43, 81, 2, 73, 29, 2, 33, 361, 81, 
361, 27, 189, 189, 1029, 189, 2133, 3137, 786, 1348, 189, 786, 6730, 28927, 
5, 10308, 57337, 12873, 786, 6730, 17593, 786, 343976, 28927, 291848, 
33412, 22521, 786, 21657, 185897, 43856, 937, 884709, 453, 97473, 386710, 
293957, 786, 277700, 54692, 4889, 461, 64479, 89949, 64851, 544047, 177986, 
461, 1001723, 135657, 1066008, 475210, 473511, 3268569, 342343, 1819491, 
6264114, 118442, 39006628, 417836, 60530, 36090, 7387565, 2666626, 782898, 
1071946, 417836, 60530, 677207307, 7414206, 2666626, 2196146, 143534244, 
188382, 1776204, 13186702, 78076485, 572920, 1235970100, 2988568, 2630696, 
1375729, 4909809] 
and going for some 7 minuts and going using invsigma from Max Alekseyev and 
a small recursion. 

Best, 
David 



On Tue, Nov 19, 2019 at 4:04 PM <michel.marcus at free.fr> wrote: 

> 
> Hello Seqfans 
> 
> 
> I am trying to compute sequence a(n) = A257670(A019278(n)) for the b-file 
> terms of A019278. 
> 
> 
> For the moment, I get: 1, 2, 2, 2, 2, 16, 21, 2, 19, 2, 64, 43, 81, 2, 73, 
> 29, 2, 33, 361, 81, 361, 27, 189, 189, 1029, 189, 2133, 3137, 786, 1348, 
> 189, 786, 6730, 28927, 5, 10308, 57337, 12873, 786, 6730, 17593, 786, 
> 343976, 28927, 291848, 33412, 22521, 786, 21657, 185897, 43856, 937, 
> 884709, ... 
> 
> 
> But this is taking more and more time. 
> Do you have an idea about how to speed things there ? 
> Thanks and regards. 
> 
> 
> MM 
> 
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> Seqfan Mailing list - http://list.seqfan.eu/ 
> 

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