OFFSET
1,1
EXAMPLE
10 is in the sequence since 10 = 3 + 7 (both prime) and 7 - 3 = 4 is semiprime.
13 is in the sequence since 13 = 2 + 11 (both prime) and 11 - 2 = 9 is semiprime.
16 is in the sequence since 16 = 3 + 13 (both prime) and 13 - 3 = 10 is semiprime.
18 is in the sequence since 18 = 7 + 11 (both prime) and 11 - 7 = 4 is semiprime.
MATHEMATICA
Flatten[Table[If[Sum[(PrimePi[i] - PrimePi[i - 1]) (PrimePi[n - i] - PrimePi[n - i - 1]) (KroneckerDelta[PrimeOmega[n - 2 i], 2]), {i, Floor[(n - 1)/2]}] > 0, n, {}], {n, 200}]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Jul 21 2019
STATUS
approved