OFFSET
0,2
COMMENTS
a(n) is the product of row n of A246867 (squarefree numbers arranged by sum of prime indices).
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).
FORMULA
EXAMPLE
The strict integer partitions of 6 are {(6), (5,1), (4,2), (3,2,1)}, with Heinz numbers {13,22,21,30}, with product 13*22*21*30 = 180180, so a(6) = 180180.
The sequence of terms together with their prime indices begins:
1: {}
2: {1}
3: {2}
30: {1,2,3}
70: {1,3,4}
2310: {1,2,3,4,5}
180180: {1,1,2,2,3,4,5,6}
21441420: {1,1,2,2,3,4,4,5,6,7}
6401795400: {1,1,1,2,2,3,3,4,5,5,6,7,8}
200984366583000: {1,1,1,2,2,2,3,3,3,4,4,5,5,6,6,7,8,9}
41615822944675980000: {1,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,5,5,6,6,7,7,8,9,10}
MATHEMATICA
Table[Times@@Prime/@(Join@@Select[IntegerPartitions[n], UnsameQ@@#&]), {n, 0, 15}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 07 2019
STATUS
approved