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 A068945 #9 Apr 09 2023 11:49:54 %S A068945 1,1,1,2,3,13,63,199,805,3155,12319,48070,186944,727997,2846645, %T A068945 11109160,43432775,169958492,665601661,2608395091 %N A068945 Number of ones in the binary expansion of A068943(n). %o A068945 (Python) %o A068945 from gmpy2 import popcount %o A068945 from math import comb, prod %o A068945 def a(n): %o A068945 return popcount(prod((n-m+1)**comb(m+n-2, m-1) for m in range(1, n+1))) %o A068945 print([a(n) for n in range(16)]) # _Michael S. Branicky_, Apr 09 2023 %Y A068945 Cf. A068943. %K A068945 base,more,nonn %O A068945 0,4 %A A068945 Francois Jooste (phukraut(AT)hotmail.com), Mar 09 2002 %E A068945 a(13)-a(17) from _Sean A. Irvine_, Feb 24 2011 %E A068945 a(0) changed to 1 and a(18)-a(19) from _Michael S. Branicky_, Apr 09 2023