Voozh

A122712

Least prime p of a quartet of 4 distinct primes {p, p+2, q, q+2} such that each digit of q is the same as the corresponding digit of p except that each 6 in p corresponds to a 9 in q and vice versa.

1061, 1667, 14561, 16691, 17657, 19961, 36341, 55631, 56207, 60167, 60917, 61151, 62981, 64151, 67577, 68711, 68897, 69737, 76367, 76961, 79691, 90617, 92681, 96737, 98867, 100361, 106451, 115601, 136397, 136991, 139367, 139661, 146057, 155861, 156677, 165047, 167267, 167861, 186647

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..39.

EXAMPLE

16691 and 16693 are twin primes, as are 19961 and 19963, so 16691 is a term.

PROG

(PARI) f(d) = my(ok=0); for (i=1, #d, if (d[i]==6, ok=1; d[i]=9, if (d[i]==9, d[i]=6))); if (ok, fromdigits(d));

isok(p) = {if (isprime(p) && isprime(p+2), my(q=f(digits(p))); isprime(q) && isprime(q+2); ); } \\ Michel Marcus, May 16 2022

CROSSREFS

Subsequence of A001359.