a(1) = number of 1-digit primes (that is, 4: 2,3,5,7); then a(n) = number of distinct n-digit prime numbers obtained by left- or right-concatenating a digit to the a(n-1) primes obtained in the previous iteration.
A298048
a(1) = number of 1-digit primes (that is, 4: 2,3,5,7); then a(n) = number of distinct n-digit prime numbers obtained by left- or right-concatenating a digit to the a(n-1) primes obtained in the previous iteration.
Terms
- a(0) =4a(1) =16a(2) =70a(3) =243a(4) =638a(5) =1450a(6) =2819a(7) =4951a(8) =7629a(9) =10677a(10) =13267a(11) =15182a(12) =15923a(13) =15796a(14) =14369a(15) =12547a(16) =10291a(17) =7939a(18) =5703a(19) =3911a(20) =2559a(21) =1595a(22) =920a(23) =561a(24) =321a(25) =167a(26) =72a(27) =37a(28) =11a(29) =6
External references
- oeis: A298048