Number of n-digit undulating alternating primes.

Terms

a(0) =4a(1) =9a(2) =23a(3) =49a(4) =175a(5) =321a(6) =1189a(7) =3025a(8) =12111a(9) =28492a(10) =113409a(11) =251513a(12) =1068440a(13) =2629980a(14) =11690210a(15) =28498852a(16) =128871588a(17) =298890814a(18) =1309837146