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 A308651 #34 Sep 30 2019 09:21:17 %S A308651 5,5,3,3,5,5,8,11,12,3,4,14,12,6,4,3,10,8,14,2,18,27,6,22,22,33,32,38, %T A308651 8,10,20,8,16,38,68,11,20,56,60,63,48,10,4,31,14,40,34,59,50,74,104, %U A308651 34,48,19,4,43,32,44,2,57,27,63,31,73,14,41,31,19,74,101,59,29,68,29,86,10,72,31,20,95,75,147,146,210,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 %N A308651 a(n+1) = k(a(n), n), where k(m, n) = (m*n) mod (m+n) and with a(1) = 5. %F A308651 a(k) = 0 for k >= 85. - _Jinyuan Wang_, Aug 26 2019 %F A308651 5 is one of the first starting values that produces rather long sequence until collapses to zero. %t A308651 a[1] = 5; a[n_] := a[n] = Mod[a[n - 1] * (n - 1), a[n - 1] + n - 1]; Array[a, 100] (* _Amiram Eldar_, Aug 29 2019 *) %o A308651 (Python) %o A308651 def k(a,b): %o A308651 return (a*b)%(a+b) %o A308651 a = [5] %o A308651 for n in range(1, 100): %o A308651 a.append(k(a[-1], n)) %o A308651 print(a) %K A308651 nonn,easy %O A308651 1,1 %A A308651 _Stefan Gog_, Aug 23 2019