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A225840
Largest number less than n occurring in Collatz trajectory starting with n.
2
1, 2, 2, 4, 5, 5, 4, 8, 8, 10, 10, 10, 13, 10, 8, 16, 17, 17, 16, 16, 20, 20, 16, 22, 20, 23, 26, 26, 23, 23, 16, 29, 26, 20, 34, 34, 34, 38, 20, 40, 32, 40, 40, 40, 40, 46, 24, 40, 44, 44, 40, 40, 53, 53, 52, 56, 52, 58, 53, 53, 61, 61, 32, 56, 58, 58, 52
OFFSET
2,2
COMMENTS
In triangle A070165: a(n)-th row is a suffix of n-th row;
a(n) = A070165(n,k) for some k with 1 <= k < A006577(n);
a(n) <> A070165(m,k) for all k with 1 <= k < A006577(n), a(n) < m < n.
MATHEMATICA
scoll[n_]:=Sort[NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n, #>1&]]; Flatten[Table[scoll[n][[Flatten[Position[scoll[n], n]-1]]], {n, 2, 68}]] (* Jayanta Basu, May 28 2013 *)
PROG
(Haskell)
a225840 n = maximum $ filter (< n) $ a070165_row n
CROSSREFS
Cf. A187831.
Sequence in context: A276299 A231302 A231363 * A361645 A319409 A122543
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, May 16 2013
STATUS
approved