# [seqfan] Re: b-files needed for some basic sequences

Robert Israel israel at math.ubc.ca
Mon Feb 7 03:32:12 CET 2011

```A propos A015617: surely there should also be a sequence for the number of
pairwise coprime triples of positive integers with largest element n,
thus A015617(n) - A015617(n-1).
The first 100 elements are
0, 0, 1, 1, 5, 1, 11, 6, 12, 5, 31, 6, 45, 14, 21, 24, 79, 15, 101, 27,
49, 37, 149, 28, 126, 56, 109, 57, 241, 28, 277, 106, 137, 100, 183, 62,
395, 128, 193, 102, 489, 65, 541, 165, 203, 189, 649, 116, 551, 170, 347,
231, 829, 147, 506, 234, 434, 307, 1027, 119, 1101, 364, 450, 412, 727,
180, 1327, 415, 658, 243, 1493, 261, 1587, 526, 572, 522, 1123, 261, 1855,
435, 997, 638, 2059, 268, 1296, 709, 1064, 646, 2367, 272, 1613, 785,
1221, 843, 1631, 457, 2805, 722, 1232, 662

Robert Israel                                israel at math.ubc.ca
Department of Mathematics        http://www.math.ubc.ca/~israel
University of British Columbia            Vancouver, BC, Canada

On Sun, 6 Feb 2011, N. J. A. Sloane wrote:

> Dear SeqFans, The following could all use b-files:
> A018805, A071778, A015616, A015617.
>
> The cross-references will show many other closely related sequences
> that also are lacking b-files. E.g. A015631, A100448, ...
>
> I would like anywhere up to 10000 terms for each, though that
> may be difficult.
>
> These days, of course, you can upload your own b-files by editing the sequence.
>
> (Oh, a while back you could not upload a b-file if a b-file
> already existed. But maybe that has been fixed now? I'm not sure.)
>
> At present none of these have b-files.
>
> Neil
>
>
> _______________________________________________
>
> Seqfan Mailing list - http://list.seqfan.eu/
>

```

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