Number of solutions to +- 1 +- 2 +- 3 +- 5 +- 7 +- ... +- prime(n-1) = 0 or 1.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =2a(5) =2a(6) =3a(7) =6a(8) =7a(9) =12a(10) =19a(11) =32a(12) =53a(13) =90a(14) =156a(15) =276a(16) =493a(17) =878a(18) =1566a(19) =2834a(20) =5146a(21) =9396a(22) =17358a(23) =32042a(24) =59434a(25) =110292a(26) =204332a(27) =380548a(28) =713601a(29) =1342448