A320909 Numbers k such that k^2 and k^3, when reversed, are prime.

89, 271, 325, 328, 890, 1025, 1055, 1081, 1129, 1169, 1241, 2657, 2710, 3112, 3121, 3149, 3244, 3250, 3263, 3280, 3335, 3346, 3403, 4193, 4222, 4231, 4289, 4291, 5531, 5584, 5653, 5678, 5716, 5791, 5795, 5836, 5837, 8882, 8900, 8926, 8942, 9664, 9794, 9875

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000 (first 100 terms from Jesse Endo Jenks)

Codewars, Square and Cube of a Number Become Prime When Reversed

Example

89 is a term since 89^2 = 7921 and 1297 is prime, and 89^3 = 704969 and 969407 is prime.

Mathematica

Select[Range[10^4], AllTrue[IntegerReverse@ {#^2, #^3}, PrimeQ] &] (* Michael De Vlieger, Oct 23 2018 *)

Prog

(PARI) isok(n) = isprime(fromdigits(Vecrev(digits(n^2)))) && isprime(fromdigits(Vecrev(digits(n^3)))); \\ Michel Marcus, Oct 23 2018
(Python)
from sympy import isprime
A320909_list = [n for n in range(1, 10**6) if isprime(int(str(n**2)[::-1])) and isprime(int(str(n**3)[::-1]))] # Chai Wah Wu, Jan 24 2019

Crossrefs

Intersection of A059007 and A059008.

Sequence in context: A140040 A008900 A238681 * A227519 A142393 A142045

Adjacent sequences: A320906 A320907 A320908 * A320910 A320911 A320912

Keyword

nonn,base

Author

Jesse Endo Jenks, Oct 23 2018

Status

approved