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A182857
Smallest number that requires exactly n iterations to reach a fixed point under the x -> A181819(x) map.
56
1, 3, 4, 6, 12, 60, 2520, 1286485200, 35933692027611398678865941374040400000
OFFSET
0,2
COMMENTS
a(9) has 296 digits.
Related to Levine's sequence (A011784): A011784(n) = A001222(a(n)) = A001221(a(n+1)) = A051903(a(n+2)) = A071625(a(n+2)). Also see A182858.
Values of n where A182850(n) increases to a record.
The multiplicity of prime(k) in a(n+1) is the k-th largest prime index of a(n), which is A296150(a(n),k). - Gus Wiseman, May 13 2018
LINKS
FORMULA
For n > 0, a(n) = A181819(a(n+1)). For n > 1, a(n) = A181821(a(n-1)).
EXAMPLE
From Gus Wiseman, May 13 2018: (Start)
Like A001462 the following sequence of multisets whose Heinz numbers belong to this sequence is a run-length describing sequence, as the number of k's in row n + 1 is equal to the k-th term of row n.
{2}
{1,1}
{1,2}
{1,1,2}
{1,1,2,3}
{1,1,1,2,2,3,4}
{1,1,1,1,2,2,2,3,3,4,4,5,6,7}
{1,1,1,1,1,1,1,2,2,2,2,2,2,3,3,3,3,3,4,4,4,4,5,5,5,5,6,6,6,7,7,7,8,8,9,9,10,10,11,12,13,14}
(End)
MATHEMATICA
Prepend[Function[m, Times@@Prime/@m]/@NestList[Join@@Table[Table[i, {Reverse[#][[i]]}], {i, Length[#]}]&, {2}, 8], 1] (* Gus Wiseman, May 13 2018 *)
KEYWORD
nonn
AUTHOR
Matthew Vandermast, Jan 05 2011
STATUS
approved