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 A234431 #26 Aug 31 2020 03:52:35
%S A234431 3,8,11,15,19,22,27,32,35,38,43,47,51,56,59,63,67,70,75,79,83,88,91,
%T A234431 94,99,104,107,111,115,118,123,128,131,134,139,143,147,152,155,158,
%U A234431 163,168,171,175,179,182,187,191,195,200,203,207,211,214,219,224,227,230,235,239,243,248,251
%N A234431 Numbers that are the sum of 2 successive evil numbers (A001969).
%C A234431 First differences are in {3, 4, 5}; 4*n - 2 <= a(n) <= 4*n. - _Charles R Greathouse IV_, Dec 26 2013
%H A234431 Amiram Eldar, <a href="/A234431/b234431.txt">Table of n, a(n) for n = 1..10000</a>
%F A234431 a(n) = A001969(n) + A001969(n + 1).
%t A234431 Total/@Partition[Select[Range[0,200],EvenQ[DigitCount[#,2,1]]&],2,1] (* _Harvey P. Dale_, Nov 02 2015 *)
%o A234431 (PARI) a(n)=4*n+hammingweight(n-1)%2+hammingweight(n)%2-2 \\ _Charles R Greathouse IV_, Dec 26 2013
%Y A234431 Cf. A001969, A003159 (indices of odd numbers in A234431), A131323 (odd numbers in A234431).
%K A234431 nonn,easy,base
%O A234431 1,1
%A A234431 _Irina Gerasimova_, Dec 26 2013