The On-Line Encyclopedia of Integer Sequences (OEIS)

A350442 revision #19

A350442

Numbers m such that 8^m reversed is prime.

8, 15, 50, 552, 668, 1011, 1163, 1215, 2199, 4230, 7231, 34310

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OFFSET

1,1

COMMENTS

From Bernard Schott, Jan 30 2022: (Start)

If k is a term, then u = 3*k is a term of A057708, because 8^k = 2^(3k).

If k is an even term, then t = 3*k/2 is a term of A350441, because 8^k = 4^(3k/2). First examples: k = 8, 50, 552, 668, 4230, 34310, ... and corresponding t = 12, 75, 828, 1002, 6345, 51465, ... (End)

LINKS

Table of n, a(n) for n=1..12.

MATHEMATICA

Select[Range[2200], PrimeQ[IntegerReverse[8^#]] &] (* Amiram Eldar, Dec 31 2021 *)

PROG

(PARI) isok(m) = isprime(fromdigits(Vecrev(digits(8^m))))

(Python)

from sympy import isprime

m = 8

for n in range (1, 2000):

if isprime(int(str(m)[::-1])):

print(n)

m *= 8

CROSSREFS

Cf. A059003, A071586.

Cf. Numbers m such that k^m reversed is prime: A057708 (k=2), A350441 (k=4), A058993 (k=5), A058994 (k=7), A058995 (k=13).

Sequence in context: A216443 A331463 A362906 * A151792 A243295 A118526

Adjacent sequences: A350439 A350440 A350441 * A350443 A350444 A350445

KEYWORD

nonn,base,more

AUTHOR

Mohammed Yaseen, Dec 31 2021

EXTENSIONS

a(10)-a(12) from Amiram Eldar, Dec 31 2021

STATUS

approved