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A348136
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Irregular triangle read by rows T(n,k) in which row n lists the first digit of every term of the trajectory of n in Collatz problem including the trajectory [1, 4, 2, 1] for n = 1.
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0
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1, 4, 2, 1, 2, 1, 3, 1, 5, 1, 8, 4, 2, 1, 4, 2, 1, 5, 1, 8, 4, 2, 1, 6, 3, 1, 5, 1, 8, 4, 2, 1, 7, 2, 1, 3, 1, 5, 2, 1, 4, 2, 1, 5, 1, 8, 4, 2, 1, 8, 4, 2, 1, 9, 2, 1, 7, 2, 1, 3, 1, 5, 2, 1, 4, 2, 1, 5, 1, 8, 4, 2, 1, 1, 5, 1, 8, 4, 2, 1, 1, 3, 1, 5, 2, 1, 4, 2, 1, 5, 1, 8, 4, 2, 1, 1, 6, 3, 1, 5, 1, 8, 4, 2, 1
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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Triangle begins:
1,4,2,1;
2,1;
3,1,5,1,8,4,2,1;
4,2,1;
5,1,8,4,2,1;
6,3,1,5,1,8,4,2,1;
7,2,1,3,1,5,2,1,4,2,1,5,1,8,4,2,1;
8,4,2,1;
9,2,1,7,2,1,3,1,5,2,1,4,2,1,5,1,8,4,2,1;
1,5,1,8,4,2,1;
1,3,1,5,2,1,4,2,1,5,1,8,4,2,1;
1,6,3,1,5,1,8,4,2,1;
1,4,2,1,5,1,8,4,2,1;
1,7,2,1,3,1,5,2,1,4,2,1,5,1,8,4,2,1;
...
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MATHEMATICA
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Prepend[Map[First@ IntegerDigits[#] &, Array[NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, #, # > 1 &] &, 11, 2], {2}], NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, 1, # > 1 &, {2, 1}]] // Flatten (* Michael De Vlieger, Oct 27 2021 *)
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CROSSREFS
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First digit of every term of A235795.
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KEYWORD
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nonn,base,tabf
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AUTHOR
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STATUS
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approved
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