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A321451
Number of integer partitions of n that cannot be partitioned into two or more blocks with equal sums.
30
1, 1, 1, 2, 2, 6, 4, 14, 8, 20, 16, 55, 22, 100, 45, 108, 64, 296, 93, 489, 145, 447, 241, 1254, 284, 1692, 487, 1492, 627, 4564, 811, 6841, 1172, 4531, 1744, 12260, 1970, 21636, 3103, 12193, 3719, 44582, 4645, 63260, 6417, 29947, 8987, 124753, 9784, 162107, 14247
OFFSET
0,4
FORMULA
a(n) = A000041(n) - A321452(n).
EXAMPLE
The a(1) = 1 through a(9) = 20 partitions:
(1) (2) (3) (4) (5) (6) (7) (8) (9)
(21) (31) (32) (42) (43) (53) (54)
(41) (51) (52) (62) (63)
(221) (411) (61) (71) (72)
(311) (322) (332) (81)
(2111) (331) (521) (432)
(421) (611) (441)
(511) (5111) (522)
(2221) (531)
(3211) (621)
(4111) (711)
(22111) (3222)
(31111) (4221)
(211111) (4311)
(5211)
(6111)
(22221)
(42111)
(51111)
(411111)
A complete list of all multiset partitions of the partition (2111) into two or more blocks is: ((1)(112)), ((2)(111)), ((11)(12)), ((1)(1)(12)), ((1)(2)(11)), ((1)(1)(1)(2)). None of these has equal block-sums, so (2111) is counted toward a(5).
On the other hand, the partition (321) can be partitioned as ((12)(3)), which has two or more blocks and equal block-sums, so (321) is not counted toward a(6).
MATHEMATICA
hwt[n_]:=Total[Cases[FactorInteger[n], {p_, k_}:>PrimePi[p]*k]];
facs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facs[n/d], Min@@#>=d&]], {d, Rest[Divisors[n]]}]];
Table[Length[Select[IntegerPartitions[n], Length[Select[facs[Times@@Prime/@#], SameQ@@hwt/@#&]]==1&]], {n, 10}]
KEYWORD
nonn
AUTHOR
Gus Wiseman, Nov 10 2018
EXTENSIONS
a(33)-a(50) from Alois P. Heinz, Nov 11 2018
STATUS
approved