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A369895 Irregular triangle of iteration steps of A063919 until the end of the terminal cycle is reached, read by rows.

%I A369895 #5 Feb 04 2024 18:27:34
%S A369895 1,2,1,3,1,4,1,5,1,6,7,1,8,1,9,1,10,8,1,11,1,12,8,1,13,1,14,10,8,1,15,
%T A369895 9,1,16,1,17,1,18,12,8,1,19,1,20,10,8,1,21,11,1,22,14,10,8,1,23,1,24,
%U A369895 12,8,1,25,1,26,16,1,27,1,28,12,8,1,29,1,30,42,54
%N A369895 Irregular triangle of iteration steps of A063919 until the end of the terminal cycle is reached, read by rows.
%e A369895 The beginning of the irregular triangle showing 3 terminal cycles ( 1 ), ( 6 ) and ( 30 42 54 ):
%e A369895   1
%e A369895   2    1
%e A369895   3    1
%e A369895   4    1
%e A369895   5    1
%e A369895   6
%e A369895   7    1
%e A369895   ...
%e A369895   14  10   8   1
%e A369895   ...
%e A369895   30  42  54
%e A369895   31  1
%e A369895   ...
%e A369895 Row 1230 contains a non-monotone iteration that ends in the 5-cycle starting at A097035(3):
%e A369895 1230, 1794, 2238, 2250, 1530, 1710, {1890, 2142, 2178, 1482, 1878 }.
%t A369895 a063919[1] = 1; (* function a[] in A063919 by Jean-François Alcover *)
%t A369895 a063919[n_] := Total[Select[Divisors[n], GCD[#, n/#] == 1 &]] - n /; n > 1
%t A369895 iter[k_] := Most[NestWhileList[a063919, k, UnsameQ, All]]
%t A369895 a369895[n_] := Map[iter, Range[n]]
%t A369895 a369895[30] (* irregular triangle *)
%t A369895 Flatten[a369895[30]] (* sequence data *)
%Y A369895 Cf. A002827, A063919, A097024, A097030, A097031, A097034, A097035, A318882, A318883.
%K A369895 nonn,tabf
%O A369895 1,2
%A A369895 _Hartmut F. W. Hoft_, Feb 04 2024