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 A020455 Primes that contain digits 1 and 7 only. 9
 7, 11, 17, 71, 1117, 1171, 1777, 7177, 7717, 11117, 11171, 11177, 11717, 11777, 17117, 71171, 71711, 71777, 77171, 77711, 1111711, 1111771, 1117111, 1117117, 1117177, 1171111, 1171117, 1171771, 1177171, 1177711, 1177717, 1711117, 1717117, 1771177 (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) FORMULA { A000040 } intersect { A276039 }. MATHEMATICA Flatten[Table[Select[FromDigits/@Tuples[{1, 7}, n], PrimeQ], {n, 7}]] (* Vincenzo Librandi, Jul 27 2012 *) PROG (MAGMA) [p: p in PrimesUpTo(1771177) | Set(Intseq(p)) subset [1, 7]]; // Vincenzo Librandi, Jul 27 2012 CROSSREFS Cf. A000040, A276039. Sequence in context: A276039 A199327 A260892 * A178617 A188074 A190689 Adjacent sequences:  A020452 A020453 A020454 * A020456 A020457 A020458 KEYWORD nonn,base AUTHOR STATUS approved

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Last modified December 12 15:11 EST 2019. Contains 329960 sequences. (Running on oeis4.)