[seqfan] Re: %C A020882 (?)

Richard Mathar mathar at strw.leidenuniv.nl
Mon Apr 12 22:53:50 CEST 2010

Following http://list.seqfan.eu/pipermail/seqfan/2010-April/004291.html

zs> Dear fellow seqfans,
zs> is it OK with %C A020882,
zs> thanks,
zs> Zak:
zs> BTW Why no b-file?

I've put a proposal of such a thing into http://www.strw.leidenuniv.nl/~mathar/progs/b020882.txt 
for further discussion.

A permutation of A020882, that is A119321, needs more terms.

In conjunction with A159781 (4 different shapes of primitive Pythagorean triangles) and A006278 (2^n
different shapes - or should the Beedassy comment read 2^(n-1)?) one may ask:
i) are there examples of hypotenuses c which appear in 6 different primitive Pythagorean triangles?
ii) does A159781 have a "faster" algorithm if the prime factorization is examined for
     prime factors of the 4k+1 class? (A correction 6429 -> 6409 in A159781 has been submitted.)


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