A318785 Numbers which are prime if each digit is replaced by its 9's complement.

2, 4, 6, 7, 10, 16, 20, 26, 28, 32, 38, 40, 46, 52, 56, 58, 62, 68, 70, 76, 80, 82, 86, 88, 92, 94, 96, 97, 112, 116, 118, 122, 136, 140, 142, 146, 160, 170, 172, 176, 178, 188, 190, 202, 212, 226, 230, 238, 242, 248, 256, 260, 266, 272, 280, 290, 298, 308, 316, 322, 326, 338, 340, 346, 352, 356, 358

Offset: 1

Author

Pierandrea Formusa, Sep 03 2018

Keywords

• nonn
• base

Examples

			32 belongs to this sequence as its 9's complement is 67, which is prime.
		

Crossrefs

Cf. A061601 (9's complement of n).

Programs

PARI

complement(n) = my(d=digits(n)); for(k=1, #d, d[k]=9-d[k]); subst(Pol(d), x, 10)
is(n) = ispseudoprime(complement(n)) \\ Felix Fröhlich, Sep 03 2018

Python

nmax=500
def is_prime(num):
    if num == 0 or num == 1: return(0)
    for k in range(2, num):
       if (num % k) == 0:
           return(0)
    return(1)
def c9(num):
    s=str(num)
    l=len(str(num))
    n=""
    for k in range(l):
        n = n+str(9-int(s[k]))
    return(int(n))
ris = ""
for i in range(2,nmax):
    if is_prime(c9(i)):
       ris = ris+str(i)+","
print(ris)