a(n) is the smallest composite number ending in 1, 3, 7, or 9 with n digits whose first n-1 digits are a(n-1).
A242299
a(n) is the smallest composite number ending in 1, 3, 7, or 9 with n digits whose first n-1 digits are a(n-1).
Terms
- a(0) =9a(1) =91a(2) =913a(3) =9131a(4) =91311a(5) =913111a(6) =9131111a(7) =91311111a(8) =913111111a(9) =9131111111a(10) =91311111111a(11) =913111111113
External references
- oeis: A242299