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%I A236846 #11 Mar 08 2014 08:52:42
%S A236846 0,1,2,3,4,0,6,7,8,5,0,11,12,13,14,0,16,0,10,19,0,9,22,0,24,25,26,15,
%T A236846 28,0,0,31,32,29,0,0,20,37,38,23,0,41,18,0,44,0,0,47,48,21,50,0,52,0,
%U A236846 30,55,56,53,0,59,0,61,62,27,64,0,58,67,0,0,0,0,40,73,74,43,76,49,46,0,0,17,82,0,36,0,0,87,88,0,0,35
%N A236846 Least inverse of A234742: a(n) = minimal k such that when it is remultiplied "upwards", from GF(2)[X] to N, the result is n, and 0 if no such k exists.
%C A236846 Apart from zero, each term occurs at most once. 91 is the smallest positive integer not present in this sequence.
%C A236846 Note that in contrast to the reciprocal case, where A234742(n) >= A236837(n) for all n [the former sequence gives the absolute upper bound for the latter], here it is not guaranteed that A234741(n) <= a(n) whenever a(n) > 0. For example, a(25)=25 and A234741(25)=17, and 25-17 = 8. On the other hand, a(75)=43, but A234741(75)=51, and 43-51 = -8.
%H A236846 Antti Karttunen, <a href="/A236846/b236846.txt">Table of n, a(n) for n = 0..8192</a>
%F A236846 a(n) = minimal k such that A234742(k) = n, and 0 if no such k exists.
%F A236846 For all n, a(n) <= n.
%o A236846 (Scheme) (define (A236846 n) (let loop ((k n) (minv 0)) (cond ((zero? k) minv) ((= (A234742 k) n) (loop (- k 1) k)) (else (loop (- k 1) minv)))))
%Y A236846 Differs from A236847 for the first time at n=91, where a(91)=35, while A236847(91)=91.
%Y A236846 A236844 gives the positions of zeros.
%Y A236846 Cf. A234742.
%Y A236846 Cf. also A236836, A236837.
%K A236846 nonn
%O A236846 0,3
%A A236846 _Antti Karttunen_, Jan 31 2014

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