%I #36 Feb 08 2022 05:08:37
%S 5,8,10,16,22,26,106,110,182,234,282,288,318,434,766,1056,1072,1462,
%T 1550,1930,3024,4330,5424,9398,10634,53094,90602,151632,384002,511638,
%U 530102,1364850,1887006,2193072,3138096,6470672,6959070
%N Numbers k with the property that their basins (as defined in A204539) are 2.
%C This sequence follows on from A204540, which lists seven values of k for which basin(k) = 1. There are 37 known values of k for which basin(k) = 2. A search of numbers up to 10,000,000 has not uncovered any further integers with this property. The possibility that there are even larger numbers with basins equal to 2 cannot be completely ruled out, but the chances of one being discovered are remote, in view of the fact that the average basin size for large values of k is approximately k/3, that is, over 2000000 in the region where the last known such integer was discovered.
%C For unknown reasons, all integers > 5 with basins equal to 1 or 2 are even.
%H Mark Dukes, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL24/Dukes/dukes3.html">Fagan's Construction, Strange Roots, and Tchoukaillon Solitaire</a>, Journal of Integer Sequences, Vol. 24 (2021), Article 21.7.1.
%H Mark Dukes, <a href="https://arxiv.org/abs/2202.02381">Fagan's Construction, Strange Roots, and Tchoukaillon Solitaire</a>, arXiv:2202.02381 [math.NT], 2022.
%Y Cf. A204539, A204540.
%K nonn,more
%O 1,1
%A _Colm Fagan_, Jan 23 2012
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