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A342960
Primes p such that p+A003132(p),(p+A003132(p))+A003132(p+A003132(p)), p-A003132(p), and (p-A003132(p))-A003132(p-A003132(p)) are prime.
1
38377, 70957, 106867, 278177, 278393, 380377, 432199, 435763, 526397, 1093159, 2025577, 2761147, 3068119, 3656129, 3672659, 5649079, 6863173, 7366453, 8083937, 9015863, 9346507, 9497353, 14198467, 15099901, 15467423, 15479273, 16020607, 16437427, 17602547, 18804173, 20020019, 20794141, 22866121
OFFSET
1,1
COMMENTS
The number of digits of p that are not divisible by 3 is divisible by 3.
LINKS
EXAMPLE
a(3) = 106867 is a term because 106867, 106867+A003132(106867) = 107053, 107053+A003132(107053) = 107137, 106867-A003132(106867) = 106681, and 106681-A003132(106681) = 106543 are all prime.
MAPLE
filter:= proc(n) local t, x, d;
if not isprime(n) then return false fi;
d:= add(t^2, t=convert(n, base, 10));
x:= n+d;
if not isprime(x) then return false fi;
if not isprime(x+add(t^2, t=convert(x, base, 10))) then return false fi;
x:= n-d;
isprime(x) and isprime(x-add(t^2, t=convert(x, base, 10)))
end proc:
select(filter, [seq(i, i=3..3*10^7, 2)]);
CROSSREFS
Contained in A179549 and A179550.
Cf. A003132.
Sequence in context: A298427 A138400 A248690 * A050777 A050765 A254852
KEYWORD
nonn,base
AUTHOR
J. M. Bergot and Robert Israel, Mar 31 2021
STATUS
approved