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A347272
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Main diagonal of the square array A347270.
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8
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1, 1, 5, 4, 2, 8, 26, 4, 52, 1, 16, 2, 1, 16, 8, 2, 4, 8, 4, 1, 4, 1, 4, 4, 4, 1, 155, 1, 4, 2, 395, 2, 1, 2, 1, 2, 1, 4, 4, 4, 668, 1, 4, 1, 4, 2, 425, 1, 1, 4, 2, 4, 2, 850, 425, 1, 1, 2, 2, 4, 2, 4858, 2429, 1, 4, 2, 1, 2, 1, 4, 2308, 4, 3644, 1, 1, 2, 1, 1, 4, 4, 4
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OFFSET
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0,3
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COMMENTS
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A347270 is related to the 3x + 1 (or Collatz) problem.
a(n) in {1, 2, 4, 5, 8, 10, 16, 26, 52, 53, 106, 155, 395, 425, 488, 668, 850, 866, 1732, 2308, 2429, 3644, 4858} for n >= 0.
a(n) in {1, 2, 4} for n >= 110. (End)
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LINKS
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MAPLE
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b:= proc(n, k) option remember; `if`(k=0, n, (j->
`if`(j::even, j/2, 3*j+1))(b(n, k-1)))
end:
a:= n-> b(n+1, n):
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MATHEMATICA
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b[n_, k_] := b[n, k] = If[k == 0, n, Function[j,
If[EvenQ[j], j/2, 3*j + 1]][b[n, k - 1]]];
a[n_] := b[n + 1, n];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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