cp's OEIS Frontend

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.

A120307 Inverse determinant of n X n matrix M[i,j] = i*j/(i+j-1).

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%I A120307 #7 Jun 24 2019 04:14:48
%S A120307 1,3,60,10500,18522000,359400888000,81408613942656000,
%T A120307 224737840779305293440000,7812628980363223707442752000000,
%U A120307 3508978524227146242839564498172672000000
%N A120307 Inverse determinant of n X n matrix M[i,j] = i*j/(i+j-1).
%F A120307 a(n) = 1/Det[ Table[ i*j/(i+j-1), {i, n}, {j, n}]]. a(n+1)/a(n) = A000891[n] = (2n)!(2n+1)! / (n! (n+1)!)^2 = (2n+1)*CatalanNumber[n]^2 = (2n+1)*A000108[n]^2 = C(2n+1,n+1)*CatalanNumber[n] = A001700[n]*A000108[n].
%F A120307 a(n) = A163085(2*n)/(2*n)!. - _Peter Luschny_, Sep 18 2012
%t A120307 Table[ 1/Det[ Table[ i*j/(i+j-1), {i, n}, {j, n}]], {n,1,12}]
%o A120307 (Sage)
%o A120307 def A120307(n): return A163085(2*n)/factorial(2*n)
%o A120307 [A120307(n) for n in (1..10)] # _Peter Luschny_, Sep 18 2012
%Y A120307 Cf. A000108, A000891, A001700.
%K A120307 nonn
%O A120307 1,2
%A A120307 _Alexander Adamchuk_, Jul 15 2006