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A095179
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Numbers whose reversed digit representation is prime.
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15
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2, 3, 5, 7, 11, 13, 14, 16, 17, 20, 30, 31, 32, 34, 35, 37, 38, 50, 70, 71, 73, 74, 76, 79, 91, 92, 95, 97, 98, 101, 104, 106, 107, 110, 112, 113, 118, 119, 124, 125, 128, 130, 131, 133, 134, 136, 140, 142, 145, 146, 149, 151, 152, 157, 160, 164, 166, 167, 170, 172
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OFFSET
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1,1
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COMMENTS
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If m is a term, then 10*m is another term. - Bernard Schott, Nov 20 2021
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LINKS
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EXAMPLE
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The number 70 in reverse is 07 = 7, which is prime.
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MAPLE
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q:= n-> (s-> isprime(parse(cat(s[-i]$i=1..length(s)))))(""||n):
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MATHEMATICA
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Select[Range[200], PrimeQ[FromDigits[Reverse[IntegerDigits[#]]]] &] (* Harvey P. Dale, Jun 13 2013 *)
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PROG
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(PARI) r(n) = for(x=1, n, y=eval(rev(x)); if(isprime(y), print1(x", "))) \ Get the reverse of the input string rev(str) = { local(tmp, j, s); tmp = Vec(Str(str)); s=""; forstep(j=length(tmp), 1, -1, s=concat(s, tmp[j])); return(s) }
(PARI) is_A095179(n)=isprime(eval(Strchr(vecextract(Vec(Vecsmall(Str(n))), "-1..1")))) \\ M. F. Hasler, Jan 13 2012
(PARI) isok(n) = isprime(fromdigits(Vecrev(digits(n)))); \\ Michel Marcus, Aug 22 2021
(Python)
from sympy import isprime
def ok(n): return isprime(int(str(n)[::-1]))
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CROSSREFS
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KEYWORD
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base,easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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