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A323784 Prime numbers such that the reverse of the balanced ternary representation is neither prime nor a negated prime.

%I A323784 #20 Jan 01 2025 22:33:28
%S A323784 3,19,23,41,47,67,79,97,107,109,113,127,131,151,157,167,191,197,211,
%T A323784 227,229,239,251,257,271,281,283,293,307,317,337,349,359,397,409,419,
%U A323784 431,433,439,461,463,491,503,521,523,557,563,571,577,587,593,617,619,631,641,647,653,659,661,673,683,701,733,743,769,787,797
%N A323784 Prime numbers such that the reverse of the balanced ternary representation is neither prime nor a negated prime.
%H A323784 Github, <a href="https://github.com/sneakyweasel/WarpPrimes">Python code repository</a>
%H A323784 Rosetta Code, <a href="http://www.rosettacode.org/wiki/Balanced_ternary">Balanced Ternary Code</a>
%H A323784 Wikipedia, <a href="https://en.wikipedia.org/wiki/Balanced_ternary">Balanced Ternary</a>
%e A323784 79 is a term:
%e A323784 79 is +00-+ in balanced ternary notation
%e A323784 +00-+ reversed is +-00+
%e A323784 +-00+ is 55 in balanced ternary notation
%e A323784 55 prime factors are 5 and 11
%e A323784 Therefore 55 is not prime.
%e A323784 Therefore the prime number 79 "warps" to the nonprime number 55.
%e A323784 This operation is reversible: 55 "warps" to 79.
%o A323784 (Python) # See Github link.
%o A323784 (PARI) d3(n) = if ((n%3)==2, n\3+1, n\3);
%o A323784 m3(n) = if ((n%3)==2, -1, n % 3);
%o A323784 t(n) = if (n==0, [0], if (abs(n) == 1, [n], concat(m3(n), t(d3(n)))));
%o A323784 f(n) = subst(Pol(Vec(t(n))), x, 3);
%o A323784 isok(n) = isprime(n) && !isprime(abs(f(n))); \\ _Michel Marcus_, Jan 29 2019
%Y A323784 Cf. A134028, A323782.
%Y A323784 Complement of A323782 among primes.
%K A323784 nonn,base
%O A323784 1,1
%A A323784 _Philippe Cochin_, Jan 28 2019