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 A257804 #9 May 13 2015 15:43:49 %S A257804 0,2,3,5,6,8,10,11,13,14,15,16,19,20,22,26,28,29,31,32,33,36,37,39,40, %T A257804 43,44,45,46,47,48,50,51,56,58,59,61,62,63,66,67,69,71,72,78,79,80,84, %U A257804 85,86,87,88,89,91,92,94,97,98,99,100,101,102,104,105,110,112,113,115,116,117,120,121,123,124,125,126,129,130 %N A257804 Positions of even numbers in A233271, the infinite trunk of inverted binary beanstalk. %C A257804 We start indexing of this sequence from 0, because a(0) = 0 is a special case, which can be conveniently ignored by considering only the terms from a(1) onward. %H A257804 Antti Karttunen, <a href="/A257804/b257804.txt">Table of n, a(n) for n = 0..8433</a> %F A257804 Other identities. For all n >= 0: %F A257804 A257808(a(n)) = n. [A257808 works as a left inverse for this injective function.] %o A257804 (Scheme, with _Antti Karttunen_'s IntSeq-library) %o A257804 (define A257804 (MATCHING-POS 0 0 (lambda (n) (even? (A233271 n))))) %o A257804 (define A257804 (MATCHING-POS 0 0 (lambda (n) (even? (A257800 n))))) %Y A257804 Complement: A257803. %Y A257804 Cf. A233271, A257800, A257806, A257808. %K A257804 nonn %O A257804 0,2 %A A257804 _Antti Karttunen_, May 12 2015