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A081851 Consider recurrence b(0) = (2n+1)/4, b(n) = b(0)*ceiling(b(n-1)); sequence gives first integer reached (or -1 if no integer is ever reached).

%I A081851 #7 Sep 24 2018 15:53:32
%S A081851 5,7,36,1711985,13,15,1700,114,168,42000323,275,324,58,62,23658393,
%T A081851 6055,58311963,9321,121770,13760,135,141,1960,344148,5734229,
%U A081851 3391007266515,8825709,23546737390632357,244,252,1526332099115586230,105432399233,27538521,5680
%N A081851 Consider recurrence b(0) = (2n+1)/4, b(n) = b(0)*ceiling(b(n-1)); sequence gives first integer reached (or -1 if no integer is ever reached).
%H A081851 Robert Israel, <a href="/A081851/b081851.txt">Table of n, a(n) for n = 2..10000</a>
%p A081851 g:= proc(n) local b0, b, count;
%p A081851   b0:= (2*n+1)/4; b:= b0;
%p A081851   for count from 1 do
%p A081851     b:= b0 * ceil(b);
%p A081851     if b::integer then return b fi
%p A081851   od
%p A081851 end proc:
%p A081851 map(g, [$2..100]); # _Robert Israel_, Sep 21 2018
%Y A081851 Cf. A073524, A081849, A081850.
%K A081851 nonn
%O A081851 2,1
%A A081851 _N. J. A. Sloane_, Apr 13 2003