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

1,1

Links

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

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 *)

Crossrefs

Sequence in context: A062669 A284290 A045710 * A139774 A007643 A259552

Adjacent sequences: A090149 A090150 A090151 * A090153 A090154 A090155

Keyword

nonn,base

Author

Robert G. Wilson v, Nov 22 2003

Status

approved