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%I #20 Feb 23 2023 07:27:29
%S 53,2477,4547,5009,7499,8831,9839,11027,24821,26393,29921,36833,46073,
%T 46769,47711,49307,53069,59621,64283,66041,79901,84017,93263,115679,
%U 133103,151121,169523,197651,207017,236807,239231,255191,259949,265271,270071,300431,330047
%N Primes p such that 1p1, 3p3, 7p7 and 9p9 are all primes.
%C All terms == 1 (mod 6). The sequence is apparently infinite. There are 16486 terms up to 10^9. - _Zak Seidov_, Jan 17 2014
%C Intersection of A069687, A069688, A069689, and A069690. - _Zak Seidov_, Jan 17 2014
%H Zak Seidov, <a href="/A059694/b059694.txt">Table of n, a(n) for n = 1..10000</a>
%e 53 is a term because 1531, 3533, 7537 and 9539 are primes.
%o (Python)
%o from sympy import isprime, nextprime
%o from itertools import islice
%o def agen(): # generator of terms
%o p = 2
%o while True:
%o sp = str(p)
%o if all(isprime(int(d+sp+d)) for d in "1379"):
%o yield p
%o p = nextprime(p)
%o print(list(islice(agen(), 40))) # _Michael S. Branicky_, Feb 23 2023
%Y Cf. A059677, A032682, A059693.
%K nonn,base
%O 1,1
%A _Patrick De Geest_, Feb 07 2001
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