Saturday, February 5, 2011

Primes and their reversals

Primes whose reversal in base 10 is also prime

2, 3, 5, 7, 11, 13, 17, 31, 37, 71, 73, 79, 97, 101, 107, 113, 131, 149, 151, 157, 167, 179, 181, 191, 199, 311, 313, 337, 347, 353, 359, 373, 383, 389, 701, 709, 727, 733, 739, 743, 751, 757, 761, 769, 787, 797, 907, 919, 929, 937, 941, 953, 967, 971, 983, 991, 1009, 1021,...





2 -> 1st ... 3 -> 2nd ... 5 -> 3rd ... 7 -> 4th ... 11 -> 5th ... 13 -> 6th ... 17 -> 7th ...
19 -> 8th ... 23 -> 9th ... 29 -> 10th ... 31 -> 11th ... 37 -> 12th ... 41 -> 13th ... 43 -> 14th 47 -> 15th ... 53 -> 16th ... 59 -> 17th ... 61 -> 18th ... 67 -> 19th ... 71 -> 20th ...
73 -> 21st ... 79 -> 22nd ... 83 -> 23th ... 89 -> 24th... 97 -> 25th ...

Notice: 37 is the 12th and 73 is the 21st: 37 -> 12 and 73 -> 21 (= 7*3). That's cool!


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