A347740 Number of compositions (ordered partitions) of n into at most 3 prime parts.

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

Links

Table of n, a(n) for n=0..70.

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 *)

Crossrefs

Cf. A000040, A023360, A098238, A121303, A347739, A347741, A347742, A347743.

Sequence in context: A133729 A244987 A171417 * A118833 A268823 A046877

Adjacent sequences: A347737 A347738 A347739 * A347741 A347742 A347743

Keyword

nonn

Author

Ilya Gutkovskiy, Sep 11 2021

Status

approved