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 A218289 #24 Oct 18 2024 14:18:53 %S A218289 6,12,12,12,210,168,504,72,198,660,1716,1092,546,336,4080,2448,5814, %T A218289 684,1596,4620,10626,6072,2760,1560,17550,9828,21924,2436,5394,14880, %U A218289 32736,17952,7854,4284,46620,25308,54834 %N A218289 Denominator of the sixth increasing diagonal of the autosequence of the second kind from (-1)^n/(n+1). %C A218289 See A194767. a(n) is a multiple of 6. The terms 6, 210, 504, 1716, 4080, 5814, ... have the form k*(k+1)*(k+2), for k = 1, 5, 7, 11, 15, 17, 21, 25, ... . %H A218289 OEIS Wiki, <a href="https://oeis.org/wiki/Autosequence">Autosequence</a> %F A218289 a(n) = A007531(n+3)/s(n) = (n+1)*(n+2)*(n+3)/s(n) where s(n) repeats 1, 2, 5, 10, 1, 2, 1, 10, 5, 2. %F A218289 a(n) = (n+1)*(n+2)*(n+3)*a(n-10)/((n-7)*(n-8)*(n-9)) for n>9 (empirical). - _Jean-François Alcover_, Nov 29 2016 %Y A218289 Cf. A208950(n+2). %K A218289 nonn %O A218289 0,1 %A A218289 _Paul Curtz_, Oct 25 2012