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 A085141 #10 Sep 15 2024 06:50:06 %S A085141 0,0,1,1,1,1,1,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4, %T A085141 4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6, %U A085141 6,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,8,8 %N A085141 Greatest nonnegative integer k such that k(3k+1)/2 <= n. %F A085141 a(n) = floor((sqrt(24n+1)-1)/6). %F A085141 a(A005449(n)) = n. %o A085141 (PARI) a(n)=if(n<0,0,(sqrtint(24*n+1)-1)\6) %Y A085141 Cf. A005449. %K A085141 nonn,easy %O A085141 0,8 %A A085141 _Michael Somos_, Jun 19 2003