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A339329
Primes p such that A001414(p-1)*A001414(p+1) == q (mod p), where q is the prime before p.
0
3, 13, 17, 29
OFFSET
1,1
COMMENTS
Next term, if any, > 2*10^8.
FORMULA
a(n) = prime(k) where A339327(k) = prime(k-1).
EXAMPLE
a(3)=17 is in the sequence because it is prime and A001414(16)*A001414(18) = 8*8 = 64 == 13 (mod 17), and 13 is the prime before 17.
MAPLE
spf:= n -> add(t[1]*t[2], t=ifactors(n)[2]):
p:= 1: R:= NULL:
while p < 10^7 do
q:= p: p:= nextprime(p);
v:= spf(p-1)*spf(p+1) mod p;
if v = q then R:= R, p fi
od:
R;
CROSSREFS
KEYWORD
nonn,bref,more
AUTHOR
Robert Israel, Nov 30 2020
STATUS
approved