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A224858
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Numbers n such that n*reversal(n)! - 1 is prime.
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0
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2, 3, 5, 7, 8, 11, 15, 30, 42, 58, 61, 64, 74, 77, 432, 500, 520, 601, 640, 675, 717, 888, 910, 940, 943, 950, 951, 957, 1210, 2100
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OFFSET
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1,1
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LINKS
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EXAMPLE
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n=15 : reversal(15)=51. (15*51!-1) = 23266781299310734203363645247039548165948895800254791679999999999999 which is prime. Hence, 15 is in sequence.
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MAPLE
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with(StringTools):KD:= proc() local a; a:=n*parse(Reverse(convert(n, string)))!-1; if isprime(a) then RETURN (n) fi: end: seq(KD(), n=1..1000);
with(StringTools):KD:=proc()local n, a, c; c:=1; for n from 1 to 1000 do; a:=n*parse(Reverse(convert(n, string)))!-1; if isprime(a) then lprint(c, n); c:=c+1; fi; od; end: KD();
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MATHEMATICA
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Select[Range[80], PrimeQ[#*IntegerReverse[#]!-1]&] (* The program generates the first 14 terms in the sequence. To generate more, increase the Range constant but the program may take a long time to run. *) (* Harvey P. Dale, Jan 31 2022 *)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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