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 A213731 #18 Jul 17 2017 01:03:21 %S A213731 1,1,0,1,1,0,0,1,1,0,2,1,0,0,0,1,1,0,2,1,0,0,2,1,0,2,1,0,0,0,0,1,1,0, %T A213731 2,1,0,0,2,1,0,2,1,0,0,0,1,2,0,1,2,0,0,1,2,0,2,1,0,0,0,0,0,1,1,0,2,1, %U A213731 0,0,2,1,0,2,1,0,0,0,1,2,0,1,2,0,0,1,2 %N A213731 a(n)=0 if n is in A055938, a(n)=1 if n is in A179016, otherwise (i.e., n is in A213717), a(n)=2. %C A213731 Those natural numbers n for which a(n)=1 belong to the infinite trunk of "Carl White's beanstalk" (see A179016), while the numbers n for which a(n)=0, are the leaves (terminal, dead-end nodes) of the same beanstalk, while those n for which a(n)=2, are non-terminal nodes in its finite tendrils. %H A213731 Antti Karttunen, <a href="/A213731/b213731.txt">Table of n, a(n) for n = 0..1024</a> %F A213731 a(n) = 2*A079559(n) - A213719(n). %o A213731 (Scheme): (define (A213731 n) (+ (A079559 n) (- (A079559 n) (A213719 n)))) %Y A213731 Cf. A179016, A213725, A213726, A213730. %K A213731 nonn %O A213731 0,11 %A A213731 _Antti Karttunen_, Nov 01 2012