[seqfan] Re: A019278 and A257670

[David Corneth]

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
>
> --
> Seqfan Mailing list - http://list.seqfan.eu/
>