The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A173914 Primes of the form R(n!-1), where R is the digit reversal. 2
 5, 911, 999138804001546121 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The next term is too large to include. Values of n are 3, 5, 19, 254, 266, ... [Charles R Greathouse IV, Feb 15 2011] The next term (a(4)) has 503 digits. - Harvey P. Dale, Jan 17 2023 LINKS EXAMPLE n=5 -> 5!-1 = 120-1=119 -> R(119)=911 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[IntegerReverse/@(Range[20]!-1), PrimeQ] (* Harvey P. Dale, Jan 17 2023 *) CROSSREFS Cf. A173913, A173915, A173916. Sequence in context: A299726 A094630 A284637 * A015940 A093853 A195627 Adjacent sequences: A173911 A173912 A173913 * A173915 A173916 A173917 KEYWORD nonn,bref,base AUTHOR Paolo P. Lava and Giorgio Balzarotti, Mar 02 2010 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified February 7 22:10 EST 2023. Contains 360132 sequences. (Running on oeis4.)