A204219 Primes whose binary reversal is not prime.

2, 19, 59, 79, 89, 103, 109, 137, 139, 149, 157, 179, 191, 211, 239, 241, 271, 281, 293, 311, 317, 347, 367, 379, 389, 397, 401, 419, 439, 457, 467, 499, 523, 541, 547, 557, 563, 569, 587, 593, 607, 613, 641, 647, 659, 673, 719, 733, 743, 751, 761, 769, 787, 809, 811, 829, 859, 863, 877, 887, 919, 929, 971, 977, 983, 991, 997

Offset: 1

Author

M. F. Hasler, Jan 13 2012

Keywords

• nonn
• base

Crossrefs

Complement of A074832 in A000040.

Cf. A076056, the base 10 equivalent.

Programs

Mathematica

a = {}; For[n = 1, n <= 1000, n++, If[PrimeQ[n], {d = Reverse[ IntegerDigits[n,2]]; If[!PrimeQ[FromDigits[d,2]], AppendTo[a, n]]}]]; a (* Hasler *)
Select[Prime[Range[170]], Not[PrimeQ[FromDigits[Reverse[IntegerDigits[#, 2]], 2]]] &] (* Alonso del Arte, Jan 13 2012 *)

PARI

forprime(p=1,1e3,if(!isprime(sum(i=1,#b=binary(p),b[i]<
				

PARI

isok(k) = isprime(k) && !isprime(fromdigits(Vecrev(binary(k)), 2)); \\ Michel Marcus, Feb 19 2021

Python

from sympy import isprime, primerange
def ok(p): return not isprime(int(bin(p)[:1:-1], 2))
def aupto(lim): return [p for p in primerange(2, lim+1) if ok(p)]
print(aupto(1000)) # Michael S. Branicky, Feb 19 2021