A090153 Primes of the form identical digits preceded by a 5.

5, 53, 59, 577, 599, 5333, 59999, 511111, 599999, 59999999, 577777777, 59999999999, 5111111111111, 53333333333333, 59999999999999, 577777777777777, 5111111111111111, 577777777777777777

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..43

Mathematica

Select[ FromDigits /@ Flatten[ Table[ PadRight[{5}, i, # ] & /@ {1, 2, 3, 4, 5, 6, 7, 8, 9}, {i, 2, 24}], 1], PrimeQ[ # ] &]
Join[{5}, Select[Flatten[Table[FromDigits[PadRight[{5}, n, k]], {n, 2, 20}, {k, {1, 3, 7, 9}}]], PrimeQ]] (* Harvey P. Dale, May 31 2020 *)

Crossrefs

Sequence in context: A088712 A257667 A045711 * A188339 A103654 A079385

Adjacent sequences: A090150 A090151 A090152 * A090154 A090155 A090156

Keyword

nonn,base

Author

Robert G. Wilson v, Nov 22 2003

Status

approved