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A332207
a(n) is the number of 3-factorizations of n.
1
1, 1, 1, 2, 1, 2, 2, 2, 2, 3, 1, 3, 2, 3, 2, 4, 1, 4, 3, 3, 2, 4, 2, 5, 3, 3, 2, 5, 2, 6, 2, 3, 3, 6, 2, 6, 3, 4, 3, 6, 1, 6, 4, 5, 3, 5, 2, 7, 4, 5, 3, 6, 2, 8, 3, 4, 3, 8, 2, 8, 4, 4, 4, 8, 3, 7, 2, 6, 4, 9, 2, 8, 3, 5, 5, 6, 2, 10, 6, 6, 3, 7, 2, 10, 4, 5, 3, 10
OFFSET
1,4
COMMENTS
See Bingham link for definitions.
LINKS
Aram Bingham, Ternary arithmetic, factorization, and the class number one problem, arXiv:2002.02059 [math.NT], 2020. See Table 1 p. 14.
MATHEMATICA
a[n_] := Block[{c=0, z=1}, While[3 z^2 - 3 z + 1 <= n, c += Length@ Solve[ x y z - (x-1) (y-1) (z-1) == n && x >= y >= z, {x, y}, Integers]; z++]; c]; Array[a, 88] (* Giovanni Resta, Feb 07 2020 *)
CROSSREFS
Cf. A014556.
Sequence in context: A215904 A083552 A326034 * A339929 A176835 A353865
KEYWORD
nonn
AUTHOR
Michel Marcus, Feb 07 2020
EXTENSIONS
More terms from Giovanni Resta, Feb 07 2020
STATUS
approved