cp's OEIS Frontend

A341738 Square array T(n,k), n >= 1, k >= 1, read by antidiagonals, where T(n,k) = sqrt( Product_{a=1..n} Product_{b=1..k-1} (4*sin((2*a-1)*Pi/(2*n))^2 + 4*sin(2*b*Pi/k)^2) ).

%I A341738 #13 Feb 19 2021 18:30:05
%S A341738 1,2,1,7,2,1,16,25,2,1,41,72,112,2,1,98,361,400,529,2,1,239,1250,4961,
%T A341738 2312,2527,2,1,576,5041,25088,77841,13456,12100,2,1,1393,18432,200999,
%U A341738 559682,1270016,78408,57967,2,1
%N A341738 Square array T(n,k), n >= 1, k >= 1, read by antidiagonals, where T(n,k) = sqrt( Product_{a=1..n} Product_{b=1..k-1} (4*sin((2*a-1)*Pi/(2*n))^2 + 4*sin(2*b*Pi/k)^2) ).
%F A341738 If k is odd, T(n,k) = A341533(n,k)/2.
%e A341738 Square array begins:
%e A341738   1, 2,     7,    16,       41,        98, ...
%e A341738   1, 2,    25,    72,      361,      1250, ...
%e A341738   1, 2,   112,   400,     4961,     25088, ...
%e A341738   1, 2,   529,  2312,    77841,    559682, ...
%e A341738   1, 2,  2527, 13456,  1270016,  12771458, ...
%e A341738   1, 2, 12100, 78408, 20967241, 292820000, ...
%o A341738 (PARI) default(realprecision, 120);
%o A341738 T(n, k) = round(sqrt(prod(a=1, n, prod(b=1, k-1, 4*sin((2*a-1)*Pi/(2*n))^2+4*sin(2*b*Pi/k)^2))));
%Y A341738 Main diagonal gives A341782.
%Y A341738 Cf. A341533, A341739, A341741.
%K A341738 nonn,tabl
%O A341738 1,2
%A A341738 _Seiichi Manyama_, Feb 18 2021