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A347740
Number of compositions (ordered partitions) of n into at most 3 prime parts.
5
1, 0, 1, 1, 1, 3, 2, 6, 5, 6, 9, 7, 11, 9, 9, 12, 13, 13, 16, 15, 16, 21, 17, 22, 21, 23, 23, 30, 19, 31, 18, 33, 22, 39, 19, 39, 29, 43, 27, 48, 15, 52, 26, 51, 30, 56, 25, 67, 31, 62, 38, 67, 30, 82, 28, 77, 36, 79, 25, 88, 33, 90, 41, 95, 25, 105, 42, 106, 40, 99, 22
OFFSET
0,6
FORMULA
a(n) = Sum_{k=1..3} A121303(n,k) for n >= 2. - Alois P. Heinz, Sep 11 2021
MATHEMATICA
Table[Length@Flatten[Permutations/@IntegerPartitions[n, 3, Prime@Range@PrimePi@n], 1], {n, 0, 70}] (* Giorgos Kalogeropoulos, Sep 12 2021 *)
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Sep 11 2021
STATUS
approved