Number of primes in the open interval between successive tribonacci numbers.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =1a(6) =1a(7) =3a(8) =5a(9) =8a(10) =12a(11) =23a(12) =38a(13) =61a(14) =109a(15) =179a(16) =312a(17) =537a(18) =920a(19) =1598a(20) =2779a(21) =4835a(22) =8461a(23) =14784a(24) =25984a(25) =45696a(26) =80505a(27) =142165a(28) =251300a(29) =444930