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 A250099 #7 Nov 12 2014 22:53:24 %S A250099 0,0,0,1,0,1,2,1,2,3,2,4,5,4,5,6,5,5,8,7,7,7,6,7,9,8,9,11,10,11,13,12, %T A250099 12,13,12,12,14,13,13,14,13,13,15,14,15,16,15,16,16,15,16,17,16,17,18, %U A250099 17,19,20,19,21,24,23,23,24,23,23,26,25,25,25,24,24,26,25 %N A250099 After A084937(n) has been computed, let m = largest term so far in A084937. Then a(n) = number of positive even integers < m that are missing from A084937 at this point. %C A250099 Running count of missing even numbers in A084937. %H A250099 N. J. A. Sloane, <a href="/A250099/b250099.txt">Table of n, a(n) for n = 1..100000</a> %e A250099 After step 7 of A084937, here is what we have: %e A250099 1 2 3 4 5 6 7 ... n %e A250099 1 2 3 5 4 7 9 ... A084937(n) %e A250099 so m = 9, and the missing even numbers < 9 are 6 and 8, so a(7) = 2. %Y A250099 Cf. A084937, A249686, A250100. See A249777, A249856, A249857 for another way of looking at this question. %K A250099 nonn %O A250099 1,7 %A A250099 _N. J. A. Sloane_, Nov 12 2014