%I #14 Mar 28 2014 23:43:48
%S 1,2,6,10,26,58,42,74,202,458,330,842,586,1354,1610,2634,6730,14922,
%T 10826,27210,19018,43594,51786,117322,84554,182858,215626,313930,
%U 477770,838218,576074,1100362,3197514,7391818,5294666,13683274,9488970,22071882,26266186
%N a(n) = binary code (shown here in decimal) of the position of the predecessor of the natural number pair (2n,2n+1) in the compact beanstalk-tree A218780.
%H A. Karttunen, <a href="/A218791/b218791.txt">Table of n, a(n) for n = 1..1024</a>
%F a(n) = A218615(A005187(n)).
%o (Scheme with memoization-macro definec): (definec (A218791 n) (cond ((< n 2) n) ((A011371 (* 2 n)) => (lambda (bp) (if (odd? bp) (A004754 (A218791 (/ (-1+ bp) 2))) (A004755 (A218791 (/ bp 2))))))))
%Y Subset of A218615, i.e., a(n) = A218615(A005187(n)).
%Y Also, a(n) = A054429(A218790(n)). (Note also how the first five or so terms are twice the terms in the beginning of A218790, shifted by one term.)
%Y Used to construct A218780, A218781. Cf. also A218787, A218788.
%K nonn,base
%O 1,2
%A _Antti Karttunen_, Nov 16 2012