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A059694
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Primes p such that 1p1, 3p3, 7p7 and 9p9 are all primes.
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4
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53, 2477, 4547, 5009, 7499, 8831, 9839, 11027, 24821, 26393, 29921, 36833, 46073, 46769, 47711, 49307, 53069, 59621, 64283, 66041, 79901, 84017, 93263, 115679, 133103, 151121, 169523, 197651, 207017, 236807, 239231, 255191, 259949, 265271, 270071, 300431, 330047
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history;
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internal format)
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OFFSET
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1,1
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COMMENTS
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All terms == 1 (mod 6). The sequence is apparently infinite. There are 16486 terms up to 10^9. - Zak Seidov, Jan 17 2014
Intersection of A069687, A069688, A069689, and A069690. - Zak Seidov, Jan 17 2014
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LINKS
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Zak Seidov, Table of n, a(n) for n = 1..10000
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EXAMPLE
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53 is a term because 1531, 3533, 7537 and 9539 are primes.
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PROG
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(Python)
from sympy import isprime, nextprime
from itertools import islice
def agen(): # generator of terms
p = 2
while True:
sp = str(p)
if all(isprime(int(d+sp+d)) for d in "1379"):
yield p
p = nextprime(p)
print(list(islice(agen(), 40))) # Michael S. Branicky, Feb 23 2023
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CROSSREFS
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Cf. A059677, A032682, A059693.
Sequence in context: A282931 A210783 A221237 * A263516 A243231 A280357
Adjacent sequences: A059691 A059692 A059693 * A059695 A059696 A059697
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KEYWORD
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nonn,base
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AUTHOR
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Patrick De Geest, Feb 07 2001
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STATUS
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approved
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