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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A321451 Number of integer partitions of n that cannot be partitioned into two or more blocks with equal sums.

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%I A321451 #11 Nov 11 2018 18:27:26
%S A321451 1,1,1,2,2,6,4,14,8,20,16,55,22,100,45,108,64,296,93,489,145,447,241,
%T A321451 1254,284,1692,487,1492,627,4564,811,6841,1172,4531,1744,12260,1970,
%U A321451 21636,3103,12193,3719,44582,4645,63260,6417,29947,8987,124753,9784,162107,14247
%N A321451 Number of integer partitions of n that cannot be partitioned into two or more blocks with equal sums.
%F A321451 a(n) = A000041(n) - A321452(n).
%e A321451 The a(1) = 1 through a(9) = 20 partitions:
%e A321451   (1)  (2)  (3)   (4)   (5)     (6)    (7)       (8)     (9)
%e A321451             (21)  (31)  (32)    (42)   (43)      (53)    (54)
%e A321451                         (41)    (51)   (52)      (62)    (63)
%e A321451                         (221)   (411)  (61)      (71)    (72)
%e A321451                         (311)          (322)     (332)   (81)
%e A321451                         (2111)         (331)     (521)   (432)
%e A321451                                        (421)     (611)   (441)
%e A321451                                        (511)     (5111)  (522)
%e A321451                                        (2221)            (531)
%e A321451                                        (3211)            (621)
%e A321451                                        (4111)            (711)
%e A321451                                        (22111)           (3222)
%e A321451                                        (31111)           (4221)
%e A321451                                        (211111)          (4311)
%e A321451                                                          (5211)
%e A321451                                                          (6111)
%e A321451                                                          (22221)
%e A321451                                                          (42111)
%e A321451                                                          (51111)
%e A321451                                                          (411111)
%e A321451 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).
%e A321451 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).
%t A321451 hwt[n_]:=Total[Cases[FactorInteger[n],{p_,k_}:>PrimePi[p]*k]];
%t A321451 facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]];
%t A321451 Table[Length[Select[IntegerPartitions[n],Length[Select[facs[Times@@Prime/@#],SameQ@@hwt/@#&]]==1&]],{n,10}]
%Y A321451 Cf. A000041, A265947, A276024, A279787, A305551, A306017, A317141, A320322, A321452, A321453, A321454, A321455.
%K A321451 nonn
%O A321451 0,4
%A A321451 _Gus Wiseman_, Nov 10 2018
%E A321451 a(33)-a(50) from _Alois P. Heinz_, Nov 11 2018