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Square array read by ascending antidiagonals: row n is the trajectory of n under the A006369 map.
2

%I #14 Dec 21 2023 05:25:06

%S 0,1,0,2,1,0,3,3,1,0,4,2,2,1,0,5,5,3,3,1,0,6,7,7,2,2,1,0,7,4,9,9,3,3,

%T 1,0,8,9,5,6,6,2,2,1,0,9,11,6,7,4,4,3,3,1,0,10,6,15,4,9,5,5,2,2,1,0,

%U 11,13,4,10,5,6,7,7,3,3,1,0,12,15,17,5,13,7,4,9,9,2,2,1,0

%N Square array read by ascending antidiagonals: row n is the trajectory of n under the A006369 map.

%H Paolo Xausa, <a href="/A368227/b368227.txt">Table of n, a(n) for n = 0..11324</a> (antidiagonals 1..150 of the array, flattened).

%H <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>

%e Array begins:

%e [ 0] 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ... = A000004

%e [ 1] 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ... = A000012

%e [ 2] 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, ... = A010693

%e [ 3] 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, ... = A176059

%e [ 4] 4, 5, 7, 9, 6, 4, 5, 7, 9, 6, 4, ... = A094328

%e [ 5] 5, 7, 9, 6, 4, 5, 7, 9, 6, 4, 5, ... = A094328 (shifted)

%e [ 6] 6, 4, 5, 7, 9, 6, 4, 5, 7, 9, 6, ... = A094328 (shifted)

%e [ 7] 7, 9, 6, 4, 5, 7, 9, 6, 4, 5, 7, ... = A094328 (shifted)

%e [ 8] 8, 11, 15, 10, 13, 17, 23, 31, 41, 55, 73, ... = A028394

%e [ 9] 9, 6, 4, 5, 7, 9, 6, 4, 5, 7, 9, ... = A094328 (shifted)

%e [10] 10, 13, 17, 23, 31, 41, 55, 73, 97, 129, 86, ... = A028394 (shifted)

%e ... | | |

%e A001477|A168222

%e A006369

%t A006369[n_]:=If[Divisible[n,3],2n/3,Round[4n/3]];

%t A368227list[dmax_]:=With[{a=Reverse[Table[NestList[A006369,n-1,dmax-n],{n,dmax}]]},Array[Diagonal[a,#]&,dmax,1-dmax]];

%t A368227list[15] (* Generates 15 antidiagonals *)

%Y Rows: A000004, A000012, A010693, A028394, A028396, A094328, A094329, A176059, A185589, A185590, A217729, A223083, A223084, A223085.

%Y Columns: A001477, A006369, A168222.

%Y Main diagonal: A368228.

%Y Cf. A368179.

%K nonn,tabl,easy

%O 0,4

%A _Paolo Xausa_, Dec 18 2023