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 A247892 #4 Sep 26 2014 13:28:11 %S A247892 1,1,2,1,3,1,4,3,4,3,7,3,8,5,8,6,11,4,12,7,11,9,15,6,15,12,16,12,20,4, %T A247892 21,15,19,16,22,10,26,18,23,17,29,11,30,22,24,24,33,16,34,22,31,25,38, %U A247892 19,36,27,35,30,43,15,44,33,36,34,44,22,49,36,43,27 %N A247892 Number of nonprimes in n-th row of triangle A077581. %C A247892 a(n) = n - A247815(n) %o A247892 (Haskell) %o A247892 a247892 n = n - a247815 n %Y A247892 Cf. A077581, A247815. %K A247892 nonn %O A247892 1,3 %A A247892 _Reinhard Zumkeller_, Sep 26 2014