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A166851 Numbers n such that reversal(n!+n) is prime. 0
1, 5, 37, 857, 2566 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

It's obvious that 1 is the only number n such that n!+n is prime.

There is no further term up to 5000.

LINKS

Table of n, a(n) for n=1..5.

EXAMPLE

37!+37=13763753091226345046315979581580902400000037 and reversal(37!+37)=

73000000420908518597951364054362219035736731 is prime so 37 is in the sequence.

MATHEMATICA

reversal[n_]:=FromDigits[Reverse[IntegerDigits[n]]];

Do[If[PrimeQ[reversal[n!+n]], Print[n]], {n, 5000}]

CROSSREFS

Sequence in context: A257952 A240186 A003213 * A090439 A089795 A081971

Adjacent sequences:  A166848 A166849 A166850 * A166852 A166853 A166854

KEYWORD

base,hard,more,nonn

AUTHOR

Farideh Firoozbakht, Oct 22 2009

STATUS

approved

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Last modified June 14 05:51 EDT 2021. Contains 345018 sequences. (Running on oeis4.)