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Date: 21-12-2019
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Date: 28-8-2020
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Date: 23-11-2020
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An emirp ("prime" spelled backwards) is a prime whose (base 10) reversal is also prime, but which is not a palindromic prime. The first few are 13, 17, 31, 37, 71, 73, 79, 97, 107, 113, 149, 157, ... (OEIS A006567). A binary plot of the emirps is illustrated above.
REFERENCES:
Gardner, M. The Magic Numbers of Dr Matrix. Buffalo, NY: Prometheus, p. 230, 1985.
Rivera, C. "Problems & Puzzles: Puzzle 020-Reversible Primes." https://www.primepuzzles.net/puzzles/puzz_020.htm.
Sloane, N. J. A. Sequence A006567/M4887 in "The On-Line Encyclopedia of Integer Sequences."
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