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 A020457 Primes that contain digits 1 and 9 only. 9
 11, 19, 191, 199, 911, 919, 991, 1999, 9199, 11119, 19919, 19991, 91199, 99119, 99191, 99991, 111119, 111191, 111919, 119191, 191119, 191911, 191999, 199999, 911111, 919111, 991999, 999199, 1111991, 1191119, 1191191, 1191199, 1191991, 1199999 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Alois P. Heinz, Table of n, a(n) for n = 1..20000 (first 1000 terms from Vincenzo Librandi) James Maynard and Brady Haran, Primes without a 7, Numberphile video (2019) MATHEMATICA Flatten[Table[Select[FromDigits/@Tuples[{1, 9}, n], PrimeQ], {n, 7}]] (* Vincenzo Librandi, Jul 27 2012 *) PROG (MAGMA) [p: p in PrimesUpTo(1199999) | Set(Intseq(p)) subset [1, 9]]; // Vincenzo Librandi, Jul 27 2012 CROSSREFS Cf. A329761. Sequence in context: A089773 A048389 A163151 * A032370 A295834 A129908 Adjacent sequences:  A020454 A020455 A020456 * A020458 A020459 A020460 KEYWORD nonn,base AUTHOR STATUS approved

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Last modified October 21 11:51 EDT 2020. Contains 337914 sequences. (Running on oeis4.)