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 A082022 #6 Apr 30 2014 01:27:34 %S A082022 1,4,18,576,1200,518400,1587600,180633600,1646023680,13168189440000, %T A082022 461039040000,229442532802560000,86553098311680000, %U A082022 3753113311877529600,834966920275488000000 %N A082022 In the following square array a(i,j) = Least Common Multiple of i and j. Sequence contains the product of the terms of the n-th antidiagonal. %C A082022 If n is even and n+1 is prime, a(n) = n^2 * (n-1)!^2. If n is odd and >3, 2*(n+1)*a(n) is a perfect square, the root of which has the factor 1/2*n*(n-1)*((n-1)/2)!. This was proved by Lawrence Sze. - _Ralf Stephan_, Nov 16 2004 %F A082022 Prod(k=1...n, lcm(k, n+1-k)). %e A082022 1 2 3 4 5... %e A082022 2 2 6 4 10... %e A082022 3 6 3 12 15... %e A082022 4 4 12 4 20... %e A082022 5 10 15 20 5... %e A082022 ... %e A082022 The same array in triangular form is %e A082022 1 %e A082022 2 2 %e A082022 3 2 3 %e A082022 4 6 6 4 %e A082022 5 4 3 4 5 %e A082022 ... %e A082022 Sequence contains the product of the terms of the n-th row. %o A082022 (PARI) for(n=1,20,p=1:for(k=1,n,p=p*lcm(k,n+1-k)):print1(p",")) %Y A082022 Cf. A006580, A003990, A082292. %Y A082022 Equals A001044(n) / A051190(n+1). %K A082022 nonn %O A082022 1,2 %A A082022 _Amarnath Murthy_, Apr 06 2003 %E A082022 Corrected and extended by _Ralf Stephan_, Apr 08 2003