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 A224858 Numbers n such that n*reversal(n)! - 1 is prime. 0
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Chris K. Caldwell and G. L. Honaker, Jr., Prime Curios! 943 EXAMPLE n=15 : reversal(15)=51. (15*51!-1) = 23266781299310734203363645247039548165948895800254791679999999999999 which is prime. Hence, 15 is in sequence. MAPLE 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(); CROSSREFS Sequence in context: A026401 A069353 A300163 * A090704 A112055 A291485 Adjacent sequences:  A224855 A224856 A224857 * A224859 A224860 A224861 KEYWORD nonn,base AUTHOR K. D. Bajpai, Jul 22 2013 EXTENSIONS a(29)-a(30) from Giovanni Resta, Jul 22 2013 STATUS approved

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Last modified August 2 17:49 EDT 2021. Contains 346428 sequences. (Running on oeis4.)