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A173913 Primes of the form R(n!+1), where R(k) is the digit reversal of k. 3
2, 3, 7, 127, 10861993, 1008634767031, 100690824786553, 100238804001546121, 1000867067777270004211, 1000000000002116896100279523601123039646103424220822837823578111551 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Next term (n=867) has 2173 digits.

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

n=6 -> 6!+1 = 720+1=721 -> Reverse_Digits(721)=127 that is prime

MAPLE

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);

MATHEMATICA

Select[FromDigits[Reverse[IntegerDigits[#]]]&/@(Range[150]!+1), PrimeQ] (* Harvey P. Dale, Jul 11 2012 *)

CROSSREFS

Cf. A173914-A173916

Sequence in context: A062935 A083436 A088856 * A007013 A103405 A087311

Adjacent sequences:  A173910 A173911 A173912 * A173914 A173915 A173916

KEYWORD

nonn,base

AUTHOR

Paolo P. Lava and Giorgio Balzarotti, Mar 02 2010

EXTENSIONS

Edited by Charles R Greathouse IV, Aug 02 2010

STATUS

approved

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Last modified September 28 21:47 EDT 2020. Contains 337414 sequences. (Running on oeis4.)