A020454 Primes that contain digits 1 and 6 only.

11, 61, 661, 6661, 11161, 16111, 16661, 66161, 111611, 161611, 611111, 616111, 1111661, 1611161, 1616161, 1616611, 1661111, 1661161, 1666111, 6111661, 6116111, 6116161, 6161161, 6611611, 6661111, 6661661, 11111161, 11166611, 11616611

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Mathematica

Flatten[Table[Select[FromDigits/@Tuples[{1, 6}, n], PrimeQ], {n, 8}]] (* Vincenzo Librandi, Jul 27 2012 *)
Select[Flatten[Table[10*FromDigits/@Tuples[{1, 6}, n]+1, {n, 7}]], PrimeQ] (* Slightly faster than the above Mathematica program by forcing the last digit to be one. *) (* Harvey P. Dale, May 31 2018 *)

Prog

(Magma) [p: p in PrimesUpTo(11616611) | Set(Intseq(p)) subset [1, 6]]; // Vincenzo Librandi, Jul 27 2012. (see Berselli A020461).

Crossrefs

Sequence in context: A088545 A259257 A289646 * A009016 A191596 A227087

Adjacent sequences: A020451 A020452 A020453 * A020455 A020456 A020457

Keyword

nonn,base

Author

David W. Wilson

Status

approved