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A020469 Primes that contain digits 6 and 7 only. 3
7, 67, 677, 67777, 76667, 76777, 666667, 677767, 767677, 777677, 6676667, 6676777, 6677677, 6677767, 6677777, 6766667, 6766777, 6776677, 7666667, 7667677, 7667767, 7766767, 7766777, 7777667, 66666667, 66677777, 66776777, 67667777, 67766767 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

MATHEMATICA

Flatten[Table[Select[FromDigits/@Tuples[{6, 7}, n], PrimeQ], {n, 8}]] (* Vincenzo Librandi, Jul 27 2012 *)

CROSSREFS

Sequence in context: A067275 A073552 A036948 * A199756 A038386 A082578

Adjacent sequences:  A020466 A020467 A020468 * A020470 A020471 A020472

KEYWORD

nonn,base

AUTHOR

David W. Wilson

STATUS

approved

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Last modified April 18 19:27 EDT 2014. Contains 240733 sequences.