This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A173585 #7 Sep 08 2022 08:45:50 %S A173585 1,1,1,1,16,1,1,225,225,1,1,3136,44100,3136,1,1,43681,8561476,8561476, %T A173585 43681,1,1,608400,1660970025,23150231104,1660970025,608400,1,1, %U A173585 8473921,322220846025,62555239000969,62555239000969,322220846025,8473921,1 %N A173585 Triangle T(n, k, q) = c(n, q)/(c(k, q)*c(n-k, q)), where c(n, q) = Product_{j=1..n} t(2*j, q), t(n, q) = (1/4)*( (2 + sqrt(q))^n + (2 - sqrt(q))^n - 2 ), and q = 3, read by rows. %H A173585 G. C. Greubel, <a href="/A173585/b173585.txt">Rows n = 0..50 of the triangle, flattened</a> %F A173585 T(n, k, q) = c(n, q)/(c(k, q)*c(n-k, q)), where c(n, q) = Product_{j=1..n} t(2*j, q), t(n, q) = (1/4)*( (2 + sqrt(q))^n + (2 - sqrt(q))^n - 2 ), and q = 3. %F A173585 From _G. C. Greubel_, Jul 06 2021: (Start) %F A173585 T(n, k, m) = b(n,m)/(b(k,m)*b(n-k,m)), where b(n, k) = (1/2^n)*Product_{j=1..n} (1 - ChebyshevT(2*j, k+1)), b(n, 0) = n!, and m = 1. %F A173585 T(n, k, m) = Product_{j=1..n-k} ( (1 - ChebyshevT(2*j+2*k, m+1))/(1 - ChebyshevT(2*j, m+1)) ) with m = 1. (End) %e A173585 Triangle begins as: %e A173585 1; %e A173585 1, 1; %e A173585 1, 16, 1; %e A173585 1, 225, 225, 1; %e A173585 1, 3136, 44100, 3136, 1; %e A173585 1, 43681, 8561476, 8561476, 43681, 1; %e A173585 1, 608400, 1660970025, 23150231104, 1660970025, 608400, 1; %t A173585 (* First program *) %t A173585 f[n_, q_]:= (1/4)*((2+Sqrt[q])^n + (2-Sqrt[q])^n -2); %t A173585 c[n_, q_]:= Product[f[k, q], {k, 2, n, 2}]//Simplify; %t A173585 T[n_, k_, q_]:= c[n, q]/(c[k, q]*c[n - k, q]); %t A173585 Table[T[n, k, 3], {n, 0, 10, 2}, {k, 0, n, 2}]//Flatten (* modified by _G. C. Greubel_, Jul 06 2021 *) %t A173585 (* Second program *) %t A173585 t[n_, q_]:= (1/4)*(Round[(2+Sqrt[q])^n + (2-Sqrt[q])^n] -2); %t A173585 c[n_, q_]:= Product[t[2*j, q], {j,n}]; %t A173585 T[n_, k_, q_]:= c[n, q]/(c[k, q]*c[n-k, q]); %t A173585 Table[T[n, k, 3], {n,0,12}, {k,0,n}]//Flatten (* _G. C. Greubel_, Jul 06 2021 *) %o A173585 (Magma) %o A173585 b:= func< n, k | n eq 0 select 1 else k eq 0 select Factorial(n) else (&*[1 - Evaluate(ChebyshevT(j), k+1)^2 : j in [1..n]]) >; %o A173585 T:= func< n,k,m | b(n,m)/(b(k,m)*b(n-k,m)) >; %o A173585 [T(n,k,1): k in [0..n], n in [0..12]]; // _G. C. Greubel_, Jul 06 2021 %o A173585 (Sage) %o A173585 @CachedFunction %o A173585 def f(n,q): return (1/4)*( round((2 + sqrt(q))^n + (2 - sqrt(q))^n) - 2 ) %o A173585 def c(n,q): return product( f(2*j, q) for j in (1..n)) %o A173585 def T(n,k,q): return c(n, q)/(c(k, q)*c(n-k, q)) %o A173585 flatten([[T(n,k,3) for k in (0..n)] for n in (0..12)]) # _G. C. Greubel_, Jul 06 2021 %Y A173585 Cf. A022168 (q=0), A022173 (q=1), this sequence (q=3). %Y A173585 Cf. A007318 (m=0), this sequence (m=1), A156645 (m=2), A156646 (m=10). %Y A173585 Cf. A123583, A156647. %K A173585 nonn,tabl %O A173585 0,5 %A A173585 _Roger L. Bagula_, Feb 22 2010 %E A173585 Edited by _G. C. Greubel_, Jul 06 2021