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A091916
Maximum of odd products of partitions of n.
2
1, 1, 1, 3, 3, 5, 9, 9, 15, 27, 27, 45, 81, 81, 135, 243, 243, 405, 729, 729, 1215, 2187, 2187, 3645, 6561, 6561, 10935, 19683, 19683, 32805, 59049, 59049, 98415, 177147, 177147, 295245, 531441, 531441, 885735, 1594323, 1594323, 2657205, 4782969, 4782969
OFFSET
0,4
FORMULA
For n>5, a(n+3) = 3a(n) (conjectured). - Ralf Stephan, Dec 02 2004
From Ron Knott, Mar 18 2020: (Start)
a(3*n) = 3^n; a(3*n+1) = a(3*n); a(3*n+2) = 5*3^(n-1) for n >= 1.
G.f.: -(2*x^5+x^2+x+1)/(3*x^3-1). (End)
EXAMPLE
The partitions of 5 are 5, 41, 32, 311, 221, 2111, 11111, with products 5, 4, 6, 3, 4, 2, 1 and the maximal odd product is 5.
MATHEMATICA
first Needs["DiscreteMath`Combinatorica`"], then f[n_] := Max[ Select[ Apply[ Times, Partitions[n], 2], OddQ[ # ] &]]; Table[ f[n], {n, 1, 43}] (* Robert G. Wilson v, Feb 12 2004 *)
Table[Max[(Times @@ #) & /@
IntegerPartitions[n, All, Range[1, n, 2]]], {n, 1, 43}]. (* Ron Knott, Mar 18 2020 *)
CROSSREFS
Sequence in context: A179437 A136791 A213933 * A102437 A319794 A072706
KEYWORD
nonn
AUTHOR
Jon Perry, Feb 12 2004
EXTENSIONS
More terms from Robert G. Wilson v, Feb 12 2004
a(0)=1 prepended by Alois P. Heinz, Mar 18 2020
STATUS
approved