a(1) = 3. For n > 1, Ulam's spiral is started with a(n-1), and the primes p on the NE spoke are considered. a(n) is the minimal p that is the lesser of a twin prime pair.
A163586
a(1) = 3. For n > 1, Ulam's spiral is started with a(n-1), and the primes p on the NE spoke are considered. a(n) is the minimal p that is the lesser of a twin prime pair.
Terms
- a(0) =3a(1) =5a(2) =17a(3) =29a(4) =41a(5) =71a(6) =101a(7) =191a(8) =281a(9) =311a(10) =617a(11) =857a(12) =1319a(13) =1451a(14) =1481a(15) =1721a(16) =2027a(17) =2267a(18) =2729a(19) =2969a(20) =2999a(21) =3461a(22) =3767a(23) =4229a(24) =4241a(25) =4271a(26) =20021a(27) =22091a(28) =22961a(29) =23201
External references
- oeis: A163586