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A350441
Numbers m such that 4^m reversed is prime.
5
2, 5, 12, 35, 75, 182, 828, 1002, 1063, 2168, 6345, 6920, 10054, 14444, 51465
OFFSET
1,1
COMMENTS
From Bernard Schott, Jan 30 2022: (Start)
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)
MATHEMATICA
Select[Range[2200], PrimeQ[IntegerReverse[4^#]] &] (* Amiram Eldar, Dec 31 2021 *)
PROG
(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
CROSSREFS
Cf. Numbers m such that k^m reversed is prime: A057708 (k=2), this sequence (k=4), A058993 (k=5), A058994 (k=7), A350442 (k=8), A058995 (k=13).
Sequence in context: A131467 A000103 A101292 * A181899 A131267 A266931
KEYWORD
nonn,base,more
AUTHOR
Mohammed Yaseen, Dec 31 2021
EXTENSIONS
a(11)-a(15) from Amiram Eldar, Dec 31 2021
STATUS
approved