[seqfan] Re: A170817, A170818 xref suggested

Maximilian Hasler maximilian.hasler at gmail.com
Wed Dec 23 21:27:56 CET 2009

On Wed, Dec 23, 2009 at 4:12 PM, Alois Heinz <heinz at hs-heilbronn.de> wrote:
> Jonathan Post schrieb:
>> A170818
>> A170817

I suggest rephrasing the "all" in

A170818  	 	 a(n) = product of all primes of form 4k+1 that divide n.

(what is meant is "with multiplicity") -
What are "all primes =1[4] dividing  25" ?
5 and 5 ?

and for completeness there should also be the =3[4] equivalent:

%o A000001 (PARI)
for(n=1,99, t=select(x->x%4==3, factor(n)[,1]); print1(prod(i=1,#t,t[i])","))

%N A000001 product of (distinct) primes of the form 4k-1 that divide n

%S A000001


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