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A219732 a(n) = (Product_{i=1..n-1} (2^i + 1)) modulo (2^n - 1).

%I A219732 #14 Jan 03 2021 15:31:22
%S A219732 0,0,1,0,1,9,1,0,74,33,1,1170,1,129,15101,0,1,187758,1,67650,615700,
%T A219732 2049,1,4793490,3247204,8193,262658,4227330,1,480000312,1,0,
%U A219732 2458463380,131073,10787055277,19903096980,1,524289,67117058,567489872400,1,2686322969514,1
%N A219732 a(n) = (Product_{i=1..n-1} (2^i + 1)) modulo (2^n - 1).
%C A219732 E. Vantieghem proved that a(n) = 1 if and only if n is an odd prime. - _Michel Marcus_, Nov 26 2012
%H A219732 E. Vantieghem, <a href="http://arxiv.org/abs/0812.2841">On a congruence only holding for primes II</a>, arXiv:0812.2841 [math.NT], 2008-2009.
%F A219732 a(n) = A028362(n) modulo (2^n - 1).
%t A219732 Join[{0}, Table[m = 2^n - 1; prod = 1; Do[prod = Mod[prod*(2^i + 1), m], {i, n - 1}]; prod, {n, 2, 40}]] (* _T. D. Noe_, Nov 27 2012 *)
%o A219732 (PARI) a(m) = {for (n=1, m, print1(prod(j=1, n-1, 2^j+1) % (2^n - 1), ", "););}
%o A219732 (PARI) a(n)=if(n>2,my(m=2^n-1);lift(prod(i=1,n-1,Mod(2,m)^i+1)),0) \\ _Charles R Greathouse IV_, Nov 26 2012
%Y A219732 Cf. A028362.
%K A219732 nonn
%O A219732 1,6
%A A219732 _Michel Marcus_, Nov 26 2012