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A337144
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n is the a(n)-th positive integer which takes its number of steps to reach 1 in the '3x+1' problem.
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2
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 2, 3, 1, 2, 1, 1, 2, 1, 1, 2, 3, 1, 2, 1, 1, 2, 1, 2, 3, 1, 2, 1, 3, 1, 2, 3, 4, 1, 1, 1, 2, 3, 2, 3, 1, 2, 2, 1, 3, 2, 4, 5, 1, 2, 2, 1, 2, 3, 2, 3, 4, 1, 1, 1, 2, 5, 3, 4, 1, 2, 3, 5, 1, 2, 4, 5, 1, 2
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OFFSET
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1,13
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LINKS
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FORMULA
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EXAMPLE
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MAPLE
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collatz:= proc(n) option remember; `if`(n=1, 0,
1 + collatz(`if`(n::even, n/2, 3*n+1)))
end:
b:= proc() 0 end:
a:= proc(n) option remember; local t;
`if`(n=1, 0, a(n-1));
t:= collatz(n); b(t):= b(t)+1
end:
seq(a(n), n=1..120);
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MATHEMATICA
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collatz[n_] := collatz[n] = If[n == 1, 0,
1 + collatz[If[EvenQ[n], n/2, 3n+1]]];
b[_] = 0;
a[n_] := a[n] = Module[{t},
If[n == 1, 0, a[n-1]];
t = collatz[n]; b[t] = b[t]+1];
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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