A090152 Primes of the form identical digits preceded by a 4.

41, 43, 47, 433, 499, 4111, 4999, 47777, 49999, 4999999, 41111111111111, 47777777777777, 499999999999999, 43333333333333333, 41111111111111111111111111, 47777777777777777777777777

Offset: 1

Author

Robert G. Wilson v, Nov 22 2003

Keywords

• nonn
• base

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..36

Programs

Mathematica

Select[ FromDigits /@ Flatten[ Table[ PadRight[{4}, i, # ] & /@ {1, 2, 3, 4, 5, 6, 7, 8, 9}, {i, 2, 24}], 1], PrimeQ[ # ] &]
Select[Flatten[Table[FromDigits[PadRight[{4},n,k]],{n,2,30},{k,{1,3,7,9}}]],PrimeQ] (* Harvey P. Dale, Apr 23 2019 *)