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A350441
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Numbers m such that 4^m reversed is prime.
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5
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2, 5, 12, 35, 75, 182, 828, 1002, 1063, 2168, 6345, 6920, 10054, 14444, 51465
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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 u = 2*m is a term of A057708, because 4^m = 2^(2*m). In fact, terms of this sequence here are half the even terms of A057708.
If m is a term that is multiple of 3, then k = 2*m/3 is a term of A350442, because 4^m = 8^(2m/3). First examples: m = 12, 75, 828, 1002, 6345, 51465, ... and corresponding k = 8, 50, 552, 668, 4230, 34310, ... (End)
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LINKS
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MATHEMATICA
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Select[Range[2200], PrimeQ[IntegerReverse[4^#]] &] (* Amiram Eldar, Dec 31 2021 *)
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PROG
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(PARI) isok(m) = isprime(fromdigits(Vecrev(digits(4^m))))
(Python)
from sympy import isprime
m = 4
for n in range (1, 2000):
if isprime(int(str(m)[::-1])):
print(n)
m *= 4
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CROSSREFS
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KEYWORD
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nonn,base,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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