OFFSET
0,3
EXAMPLE
The a(1) = 1 through a(8) = 18 integer partitions:
(1) (2) (3) (4) (5) (6) (7) (8)
(11) (21) (22) (32) (33) (52) (44)
(111) (31) (41) (42) (61) (53)
(211) (221) (51) (331) (71)
(1111) (311) (222) (421) (422)
(2111) (321) (511) (521)
(11111) (411) (2221) (611)
(2211) (3211) (2222)
(3111) (4111) (3311)
(21111) (22111) (4211)
(111111) (31111) (5111)
(211111) (22211)
(1111111) (32111)
(41111)
(221111)
(311111)
(2111111)
(11111111)
Missing from the list for n = 7 through 9:
(43) (62) (54)
(322) (332) (63)
(431) (432)
(3221) (522)
(621)
(3222)
(3321)
(4311)
(32211)
MATHEMATICA
Table[Length[Select[IntegerPartitions[n], SameQ@@Last/@FactorInteger[Times@@#]&]], {n, 30}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Dec 14 2018
STATUS
approved