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A338821
Primes prime(k) such that A338820(k) is prime.
3
23, 53, 73, 139, 277, 281, 283, 307, 313, 347, 359, 383, 449, 571, 733, 751, 947, 1013, 1049, 1129, 1151, 1259, 1381, 1559, 1621, 1693, 1973, 2087, 2089, 2111, 2251, 2477, 2539, 2579, 2593, 2693, 2801, 2803, 2917, 3001, 3121, 3217, 3373, 3511, 3617, 3797, 4013, 4261, 4463, 4549, 4567, 4639, 4643
OFFSET
1,1
COMMENTS
Primes p such that the sum of (q^2 mod p) for primes q < p is prime.
LINKS
EXAMPLE
a(3) = 73 because it is prime and (2^2 mod 73) + (3^2 mod 73) + (5^2 mod 73) + ... + (71^2 mod 73) = 661 is prime. 73 = prime(21) where A338820(21) = 661, and this is the third prime value in A338820.
MAPLE
N:= 1000: # for terms in the first N primes
P:= [seq(ithprime(i), i=1..N)]:
R:= NULL:
for n from 1 to N do
v:= add(P[i]^2 mod P[n], i=1..n-1);
if isprime(v) then R:= R, P[n] fi
od:
R;
CROSSREFS
Sequence in context: A113912 A327920 A055782 * A104802 A128473 A132235
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Nov 10 2020
STATUS
approved