cp's OEIS Frontend

A226619 Irregular array read by rows in which row n lists the integers k, in ascending order, for which there is a primitive cycle of n positive integers under iteration by the Collatz-like 3x+k function.

%I A226619 #5 Jul 02 2013 23:57:26
%S A226619 -1,1,1,-1,5,-11,7,13,-49,5,23,29,-179,-17,11,37,55,61,-601,-115,17,
%T A226619 47,101,119,125,-1931,-473,13,25,35,175,229,247,253,-6049,-1675,-217,
%U A226619 -31,97,269,431,485,503,509,-18659,-5537,-1163,-791,59,71,145,203,295,781,943,997,1015,1021
%N A226619 Irregular array read by rows in which row n lists the integers k, in ascending order, for which there is a primitive cycle of n positive integers under iteration by the Collatz-like 3x+k function.
%C A226619 A cycle is called primitive if its elements are not a common multiple of the elements of another cycle.
%C A226619 The 3x+k function T_k is defined by T_k(x) = x/2 if x is even, (3x+k)/2 if x is odd, where k is odd.
%C A226619 For primitive cycles, GCD(k,6)=1.
%C A226619 We associate the cycle {0} with k = A226606(2) = 1.
%C A226619 For n>1 the first term of row n is 2^n-3^(n-1), and the last term is A036563(n) = 2^n-3.
%H A226619 Geoffrey H. Morley, <a href="/A226619/b226619.txt">Rows 1..26 of array, flattened</a>
%e A226619 The irregular array starts:
%e A226619 -1, 1;
%e A226619 1;
%e A226619 -1, 5;
%e A226619 -11, 7, 13;
%e A226619 -49, 5, 23, 29; ...
%Y A226619 Cf. A226605, A226606, A226618, A226620, A226621.
%K A226619 sign,tabf
%O A226619 1,5
%A A226619 _Geoffrey H. Morley_, Jul 02 2013