A347739 - OEIS

%I #9 Sep 12 2021 09:49:50

%S 1,0,1,1,1,3,1,3,2,2,3,1,2,3,3,2,4,1,4,3,4,2,5,1,6,2,5,0,4,1,6,3,4,2,

%T 7,0,8,1,3,2,6,1,8,3,6,2,7,1,10,2,8,0,6,1,10,2,6,0,7,1,12,3,5,2,10,0,

%U 12,1,4,2,10,1,12,3,9,2,10,0,14,1,8

%N Number of compositions (ordered partitions) of n into at most 2 prime parts.

%F a(n) = Sum_{k=1..2} A121303(n,k) for n >= 2. - _Alois P. Heinz_, Sep 11 2021

%t Table[Length@Flatten[Permutations/@IntegerPartitions[n,2,Prime@Range@PrimePi@n],1],{n,0,100}] (* _Giorgos Kalogeropoulos_, Sep 12 2021 *)

%Y Cf. A000040, A023360, A073610, A121303, A347740, A347741, A347742, A347743.

%K nonn

%O 0,6

%A _Ilya Gutkovskiy_, Sep 11 2021