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A104914 Numbers n such that the string 987654321k is prime. 8
1, 7, 37, 67, 77, 91, 109, 113, 133, 193, 197, 223, 317, 319, 331, 347, 371, 397, 403, 449, 491, 529, 569, 571, 587, 611, 623, 649, 673, 737, 743, 757, 767, 769, 851, 883, 893, 917, 919, 931, 989, 991, 1001, 1019, 1021, 1033, 1081, 1091, 1121, 1127, 1141 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
MATHEMATICA
With[{r = Reverse@ Range@ 9}, Select[Range[1200], PrimeQ[FromDigits[r ~Join~ IntegerDigits@ #]] &]] (* Michael De Vlieger, Jan 20 2018 *)
Select[Range[1200], PrimeQ[987654321*10^IntegerLength[#]+#]&] (* Harvey P. Dale, Jul 31 2018 *)
PROG
(Magma) [ n: n in [1..1750] | IsPrime(Seqint(Intseq(n) cat [1, 2, 3, 4, 5, 6, 7, 8, 9])) ]; // Vincenzo Librandi, Feb 02 2011
CROSSREFS
Cf. A104915.
Sequence in context: A336494 A361485 A086110 * A032588 A123084 A123085
KEYWORD
nonn,base
AUTHOR
Zak Seidov, Mar 29 2005
STATUS
approved

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Last modified June 14 20:28 EDT 2024. Contains 373401 sequences. (Running on oeis4.)