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 A135212 #10 Oct 02 2016 07:38:39
%S A135212 1,1,2,4,8,576,1152,2304,4608,18432,552960,59719680,2388787200,
%T A135212 100329062400,200658124800,802632499200,1605264998400,288947699712000,
%U A135212 6356849393664000,444979457556480000,10679506981355520000
%N A135212 a(n) = A078456(n)/A120271(n).
%H A135212 G. C. Greubel, <a href="/A135212/b135212.txt">Table of n, a(n) for n = 1..250</a>
%F A135212 a(n) = A078456(n)/A120271(n).
%t A135212 Table[ Det[ DiagonalMatrix[ Table[ Prime[i+1]-1, {i, 1, n-1} ] ] + 1 ], {n, 1, 50} ] / Numerator[ Table[ Sum[ 1/(Prime[i]-1), {i, 1, n} ], {n, 1, 50}] ]
%o A135212 (PARI) a(n) = matdet(matrix(n-1, n-1, j, k, if (j==k, prime(j+1), 1)))/numerator(sum(k=1, n, 1/(prime(k)-1))); \\ _Michel Marcus_, Oct 02 2016
%Y A135212 Cf. A078456, A120271.
%K A135212 nonn
%O A135212 1,3
%A A135212 _Alexander Adamchuk_, Nov 23 2007