Number of length n 1..(2+2) arrays with no leading or trailing partial sum equal to a prime.

Terms

a(0) =2a(1) =1a(2) =2a(3) =6a(4) =11a(5) =27a(6) =53a(7) =133a(8) =310a(9) =691a(10) =1722a(11) =4898a(12) =13169a(13) =31188a(14) =68247a(15) =151695a(16) =355719a(17) =880650a(18) =2386625a(19) =7052660a(20) =20845775a(21) =57431942a(22) =145661869a(23) =346176887a(24) =792710311a(25) =1828054653a(26) =4509979089a(27) =12381748520a(28) =37284100779a(29) =117101693844