Position of second appearance of 2n in the sequence of prime gaps A001223; if 2n does not appear at least twice, a(n) = -1.
A356221
Position of second appearance of 2n in the sequence of prime gaps A001223; if 2n does not appear at least twice, a(n) = -1.
Terms
- a(0) =3a(1) =6a(2) =11a(3) =72a(4) =42a(5) =47a(6) =62a(7) =295a(8) =180a(9) =259a(10) =297a(11) =327a(12) =446a(13) =462a(14) =650a(15) =1315a(16) =1059a(17) =1532a(18) =4052a(19) =2344a(20) =3732a(21) =3861a(22) =8805a(23) =7234a(24) =4754a(25) =2810a(26) =4231a(27) =14124a(28) =5949a(29) =9834
External references
- oeis: A356221