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Search: id:A166851
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| A166851 |
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Numbers n such that reversal(n!+n) is prime. |
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+0
1
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OFFSET
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1,2
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COMMENT
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It's obvious that 1 is the only number n such that n!+n is prime.
There is no further term up to 5000.
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EXAMPLE
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37!+37=13763753091226345046315979581580902400000037 and reversal(37!+37)=
73000000420908518597951364054362219035736731 is prime so 37 is in the sequence.
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MATHEMATICA
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reversal[n_]:=FromDigits[Reverse[IntegerDigits[n]]];
Do[If[PrimeQ[reversal[n!+n]], Print[n]], {n, 5000}]
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CROSSREFS
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Sequence in context: A121834 A083846 A003213 this_sequence A090439 A089795 A081971
Adjacent sequences: A166848 A166849 A166850 this_sequence A166852 A166853 A166854
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KEYWORD
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base,hard,more,nonn
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AUTHOR
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F. Firoozbakht (mymontain(AT)yahoo.com), Oct 22 2009
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