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 A084971 #2 Mar 30 2012 17:30:55
%S A084971 2,6,-60,1680,0,0,-261381120,101807946240,11565134380800,
%T A084971 -5051536473984000,1677391670412057600,-123625460444389263360,
%U A084971 -78207720091833771479040,16848446417200616007229440,-2300367963201102480473948160
%N A084971 Determinant of the leading n X n submatrix of A083140.
%t A084971 d[n_] := Block[{k = n}, Det[ Join[ {Table[2i, {i, 1, k}]}, Table[ Take[ Prime[j]*Select[ Range[1000], GCD[ Prime[k] #, Product[ Prime[i], {i, 1, j - 1}]] == 1 &], k], {j, 2, k}]]]]; Table[ d[n], {n, 1, 15}]
%Y A084971 Cf. A083140.
%K A084971 sign
%O A084971 1,1
%A A084971 _Robert G. Wilson v_, Jun 15 2003