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A173913
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Primes of the form R(n!+1), where R(k) is the digit reversal of k.
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3
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2, 3, 7, 127, 10861993, 1008634767031, 100690824786553, 100238804001546121, 1000867067777270004211, 1000000000002116896100279523601123039646103424220822837823578111551
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OFFSET
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1,1
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COMMENTS
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Next term (n=867) has 2173 digits.
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LINKS
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Table of n, a(n) for n=1..10.
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EXAMPLE
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n=6 -> 6!+1 = 720+1=721 -> Reverse_Digits(721)=127 that is prime
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MAPLE
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P:=proc(i) local a, b, k, n, v; v:=array(1..10000); for n from 1 by 1 to i do a:=1; k:=n!+1; while k>0 do v[a]:=k-(trunc(k/10)*10); k:=trunc(k/10); a:=a+1; od; k:=0; for b from a-1 by -1 to 1 do k:=k+v[b]*10^(a-1-b); od; if isprime(k) then print(k); fi; od; end: P(2000);
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MATHEMATICA
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Select[FromDigits[Reverse[IntegerDigits[#]]]&/@(Range[150]!+1), PrimeQ] (* Harvey P. Dale, Jul 11 2012 *)
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CROSSREFS
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Cf. A173914-A173916
Sequence in context: A062935 A083436 A088856 * A007013 A103405 A087311
Adjacent sequences: A173910 A173911 A173912 * A173914 A173915 A173916
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KEYWORD
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nonn,base
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AUTHOR
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Paolo P. Lava and Giorgio Balzarotti, Mar 02 2010
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EXTENSIONS
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Edited by Charles R Greathouse IV, Aug 02 2010
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STATUS
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approved
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