OFFSET
1,2
COMMENTS
The Heinz number of an integer partition or multiset {y_1,...,y_k} is prime(y_1)*...*prime(y_k).
There is exactly one entry with any given sum of prime indices A056239.
EXAMPLE
The sequence of terms together with their prime indices begins:
1: {}
2: {1}
3: {2}
6: {1,2}
7: {4}
13: {6}
20: {1,1,3}
29: {10}
37: {12}
39: {2,6}
42: {1,2,4}
53: {16}
61: {18}
79: {22}
107: {28}
110: {1,3,5}
113: {30}
151: {36}
173: {40}
181: {42}
199: {46}
239: {52}
261: {2,2,10}
271: {58}
281: {60}
312: {1,1,1,2,6}
For example, the divisors of 8 are {1,2,4,8}, with differences {1,2,4}, with Heinz number 42, so 42 belongs to the sequence.
MATHEMATICA
nn=1000;
Select[Union[Table[Times@@Prime/@Differences[Divisors[n]], {n, nn}]], #<=nn&]
CROSSREFS
A permutation of A328023.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Oct 02 2019
STATUS
approved