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 A158043 #9 Nov 27 2015 00:33:16 %S A158043 120,207600,96647880,30798705600,8636938282920,2309545097941200, %T A158043 608543327609001240,160948481103837273600,43112754053898172364280, %U A158043 11708778018848186302158000,3213002829193456223967295560 %N A158043 Determinant of power series of gamma matrix with determinant 5!. %C A158043 a(n) = Determinant(A + A^2 + A^3 + A^4 + A^5 + ... + A^n) %C A158043 where A is the submatrix A(1..6,1..6) of the matrix with factorial determinant %C A158043 A = [[1,1,1,1,1,1,...], [1,2,1,2,1,2,...], [1,2,3,1,2,3,...], [1,2,3,4,1,2,...], [1,2,3,4,5,1,...], [1,2,3,4,5,6,...], ...]; note: Determinant A(1..n,1..n) = (n-1)!. %D A158043 G. Balzarotti and P. P. Lava, Le sequenze di numeri interi, Hoepli, 2008. %e A158043 a(1) = Determinant(A) = 5! = 120. %p A158043 seq(Determinant(sum(A^i,i=1..n)),n=1..30); %Y A158043 Cf. A111490, A158040, A158041, A158042. %K A158043 nonn %O A158043 0,1 %A A158043 _Giorgio Balzarotti_ & _Paolo P. Lava_, Mar 11 2009