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A236836 The least inverse of A234741: a(n) = the smallest k such that A234741(k) = n, and 0 if no such k exists.

%I A236836 #9 Feb 07 2014 10:44:35
%S A236836 0,1,2,3,4,5,6,7,8,21,10,11,12,13,14,15,16,17,42,19,20,49,22,23,24,0,
%T A236836 26,35,28,29,30,31,32,93,34,91,84,37,38,55,40,41,98,43,44,105,46,47,
%U A236836 48,77,0,51,52,53,70,0,56,65,58,59,60,61,62,147,64,245,186,67,68,121
%N A236836 The least inverse of A234741: a(n) = the smallest k such that A234741(k) = n, and 0 if no such k exists.
%C A236836 A234741(a(n)) = n if n is not in A236834, in which case a(n)=0.
%H A236836 Antti Karttunen, <a href="/A236836/b236836.txt">Table of n, a(n) for n = 0..8192</a>
%F A236836 a(2^n) = 2^n.
%F A236836 a(2n) = 2*a(n).
%F A236836 If n is in A236835, a(n) < A236837(n), otherwise a(n) = A236837(n).
%o A236836 (Scheme, finding the smallest inverse empirically with a naive loop. A234742 gives an absolute upper bound for any inverse of A234741):
%o A236836 (define (A236836 n) (let ((u (A234742 n))) (let loop ((i 0)) (let ((k (A234741 i))) (cond ((> k u) 0) ((= k n) i) (else (loop (+ i 1))))))))
%Y A236836 A236834 gives the positions of zeros.
%Y A236836 Cf. A236833, A236835, A236837 (the greatest inverse of A234741).
%K A236836 nonn
%O A236836 0,3
%A A236836 _Antti Karttunen_, Jan 31 2014