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A327697
Number of refinement sequences n -> ... -> {1}^n, where in each step every single part of a nonempty selection of parts is replaced by a partition of itself into smaller parts (in weakly decreasing order).
4
1, 1, 2, 7, 22, 122, 598, 4683, 31148, 292008, 2560274, 30122014, 313694962, 4189079688, 53048837390, 826150653479, 11827659365138, 204993767192252, 3371451881544534, 65337695492942258, 1198123466804343518, 25318312971995895392, 516420623159289735874
OFFSET
1,3
EXAMPLE
a(1) = 1:
1
a(2) = 1:
2 -> 11
a(3) = 2:
3 -> 111
3 -> 21 -> 111
a(4) = 7:
4 -> 1111
4 -> 211 -> 1111
4 -> 31 -> 1111
4 -> 31 -> 211 -> 1111
4 -> 22 -> 1111
4 -> 22 -> 112 -> 1111
4 -> 22 -> 211 -> 1111
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Sep 22 2019
STATUS
approved