OFFSET
1,6
LINKS
EXAMPLE
a(12) = 4; The partitions of 12 into two distinct parts are (11,1), (10,2), (9,3), (8,4) and (7,5). Of these partitions, the parts in (11,1), (10,2), (9,3) and (8,4) are not both prime, so a(12) = 4.
MATHEMATICA
Table[Sum[1 - (PrimePi[i] - PrimePi[i - 1]) (PrimePi[n - i] - PrimePi[n - i - 1]), {i, Floor[(n - 1)/2]}], {n, 80}]
Table[Count[IntegerPartitions[n, {2}], _?(#[[1]]!=#[[2]]&&Total[Boole[ PrimeQ[ #]]]<2&)], {n, 70}] (* Harvey P. Dale, May 18 2021 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, Nov 24 2017
STATUS
approved