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 A249040 #7 Nov 11 2014 10:58:28 %S A249040 0,1,2,2,2,2,3,3,4,5,6,7,7,8,9,9,9,10,10,10,10,10,10,11,11,11,11,12, %T A249040 12,13,14,14,14,15,15,16,17,18,18,19,20,21,22,23,24,24,25,26,27,28,28, %U A249040 29,30,30,30,31,31,32,33,34,34,35,36,36,36,37,37,37,37,38,38,39,40,40,40,41,41 %N A249040 Number of even terms in first n terms of A249039. %H A249040 Reinhard Zumkeller, <a href="/A249040/b249040.txt">Table of n, a(n) for n = 1..10000</a> %F A249040 For n > 1: a(n) = a(n-1) + 1 - A249039(n) mod 2. - _Reinhard Zumkeller_, Nov 11 2014 %p A249040 See A249039. %o A249040 (Haskell) %o A249040 a249040 n = a249040_list !! (n-1) %o A249040 a249040_list = tail $ scanl (\i j -> i + 1 - mod j 2) 0 a249039_list %o A249040 -- _Reinhard Zumkeller_, Nov 11 2014 %Y A249040 Cf. A249039, A249041. %K A249040 nonn %O A249040 1,3 %A A249040 _N. J. A. Sloane_, Oct 26 2014