login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Number of partitions of n into at most 2 distinct nonprime parts.
5

%I #8 Nov 27 2022 11:04:45

%S 1,1,0,0,1,1,1,1,1,2,3,1,2,2,3,3,4,2,4,3,4,4,6,3,6,5,7,5,7,5,8,6,7,7,

%T 10,7,11,7,9,9,11,8,12,9,11,10,13,9,14,11,14,11,14,11,16,13,15,13,17,

%U 13,19,14,16,15,19,15,21,15,17,17,21,16,22,17,21,18,22,18,25,18,22

%N Number of partitions of n into at most 2 distinct nonprime parts.

%F For n > 0, a(n) = A005171(n) + A302479(n).

%o (PARI) A358638(n) = if(n<2,1,!isprime(n)+sum(k=1,(n-1)\2,!(isprime(k)+isprime(n-k)))); \\ _Antti Karttunen_, Nov 25 2022

%Y Cf. A005171, A018252, A096258, A302479, A347788, A358639, A358640.

%K nonn

%O 0,10

%A _Ilya Gutkovskiy_, Nov 24 2022