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 A198146 Primes remaining primes under map 2<=>9 (interchange of decimal digits 2 and 9). 0
 2293, 2393, 2591, 2693, 2791, 2903, 2957, 5297, 5927, 7297, 7927, 8293, 8923, 9203, 9257, 9323, 9521, 9623, 9721, 9923, 12491, 12497, 12907, 12911, 12967, 12973, 13291, 13921, 14293, 14923, 17291, 17293, 17921, 17923, 19207, 19211, 19267, 19273, 19421, 19427 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Only primes containing at least one "2" and one "9" are considered. Inspired by history (told by VIA himself) that most often mistakes made by V. I. Arnold were caused by mixing 2's and 9's (and also 3's and 5's) in the lengthy calculations by hand. LINKS Table of n, a(n) for n=1..40. V. I. Arnold, Experimental observation of mathematical facts (in Russian) EXAMPLE 2293, 9923 both primes; 2393, 9323 both primes. MATHEMATICA p = 29; Reap[Do[id = IntegerDigits[p]; If[Count[id, 2] > 0 && Count[id, 9] > 0 && PrimeQ[FromDigits[(id /. {2 -> a, 9 -> 2}) /. {a -> 9}]], Sow[p]]; p = NextPrime[p], {10^4}]][[2, 1]] CROSSREFS Cf. A198047 (map 3 <=> 5). Sequence in context: A247990 A206103 A251302 * A020404 A180454 A216899 Adjacent sequences: A198143 A198144 A198145 * A198147 A198148 A198149 KEYWORD nonn,base AUTHOR Zak Seidov, Oct 21 2011 STATUS approved

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Last modified September 23 13:16 EDT 2023. Contains 365551 sequences. (Running on oeis4.)