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 A257507 #12 May 04 2015 02:15:25 %S A257507 1,3,4,7,10,10,11,15,18,18,22,23,25,25,26,31,34,34,38,39,41,41,46,47, %T A257507 49,50,54,54,56,56,57,63,66,66,70,71,73,73,78,79,81,82,86,86,88,88,94, %U A257507 95,97,98,102,102,104,105,110,110,113,116,117,117,119,119,120,127,130,130,134,135,137,137,142,143,145,146 %N A257507 Row 2 of A257264: a(n) = A011371(A055938(n)). %C A257507 The sequence gives the parent node of each leaf-vertex (A055938) in binary beanstalk. %H A257507 Antti Karttunen, <a href="/A257507/b257507.txt">Table of n, a(n) for n = 1..16384</a> %H A257507 Paul Tek, <a href="/A179016/a179016.png">Illustration of how natural numbers in range 0 .. 133 are organized as a binary tree in the binary beanstalk</a> %F A257507 a(n) = A011371(A055938(n)). %e A257507 Terms of A055938 are the leaf-nodes in Paul Tek's illustration. This sequence gives the corresponding parent-node (in that illustration a node immediately below where the arrow points), for each term of A055938[1..]: 2, 5, 6, 9, 12, 13, 14, ... %e A257507 As A055938(4) = 9, and 9's parent node is 7 (because A011371(9) = 7), a(4) = 7. %e A257507 As A055938(5) = 12, and 12's parent node is 10, a(5) = 10. %e A257507 As A055938(6) = 13, and 13's parent node is 10, a(6) = 10. %o A257507 (Scheme) (define (A257507 n) (A011371 (A055938 n))) %Y A257507 Row 2 of A257264. %Y A257507 Cf. A011371, A055938. %Y A257507 Cf. A257508 (same sequence with duplicates removed), A257512 (the terms which occur twice). %K A257507 nonn %O A257507 1,2 %A A257507 _Antti Karttunen_, May 03 2015