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 A068630 #9 Oct 27 2019 05:09:34 %S A068630 0,1,3,0,4,9,9,16,8,17,27,38,38,51,65,65,81,98,98,117,137,158,158,181, %T A068630 205,205,231,231,231,260,260,291,323,356,356,391,427,464,464,503,543, %U A068630 584,584,627,627,627,673,720,672,672,672,672,672,725,779,834,834,834 %N A068630 a(0)=0; a(n) = n + a(n-1) if gcd(n,a(n-1)) = 1 or a(n-1) = 0; a(n) = a(n-1) - n if n divides a(n-1), otherwise a(n) = a(n-1). %Y A068630 Cf. A068626, A068627, A068628, A068629. %K A068630 easy,nonn %O A068630 0,3 %A A068630 _Amarnath Murthy_, Feb 26 2002 %E A068630 Offset and a(55)-a(57) corrected by _Gionata Neri_, Mar 23 2017