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A140211 a(n) = Product_{d == 3 (mod 4) and d|n} d.

%I A140211 #19 Jan 07 2021 07:01:04
%S A140211 1,1,3,1,1,3,7,1,3,1,11,3,1,7,45,1,1,3,19,1,21,11,23,3,1,1,81,7,1,45,
%T A140211 31,1,33,1,245,3,1,19,117,1,1,21,43,11,45,23,47,3,7,1,153,1,1,81,605,
%U A140211 7,57,1,59,45,1,31,1323,1,1,33,67,1,69,245,71,3,1,1,3375,19,77,117,79,1,81,1
%N A140211 a(n) = Product_{d == 3 (mod 4) and d|n} d.
%H A140211 J. Mulder, <a href="/A140211/b140211.txt">Table of n, a(n) for n = 1..20000</a>
%F A140211 a(n) | A007955(n). - _R. J. Mathar_, May 26 2016
%p A140211 A140211 := proc(n)
%p A140211     a := 1;
%p A140211     for d in numtheory[divisors](n) do
%p A140211         if modp(d,4) = 3 then
%p A140211             a := a*d ;
%p A140211         end if;
%p A140211     end do:
%p A140211     a;
%p A140211 end proc: # _R. J. Mathar_, Dec 15 2015
%t A140211 ListProduct[lst_] := Fold[Times, 1, lst] lst = {}; For[n = 1, n <= 1000, n++, AppendTo[lst, ListProduct[Select[Divisors[n], Mod[ #, 4] == 3 &]]]] lst (* Jasper Mulder (jasper.mulder(AT)planet.nl), Jul 15 2009 *)
%o A140211 (PARI) a(n) = my(p=1); fordiv(n, d, if ((d % 4)==3, p*=d)); p; \\ _Michel Marcus_, Jan 07 2021
%Y A140211 Cf. A140210, A007955.
%K A140211 nonn,easy
%O A140211 1,3
%A A140211 _R. J. Mathar_, Jun 27 2008