A338821 Primes prime(k) such that A338820(k) is prime.

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

Robert Israel, Table of n, a(n) for n = 1..3700

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

Cf. A338102, A338820.

Sequence in context: A113912 A327920 A055782 * A104802 A128473 A132235

Adjacent sequences: A338818 A338819 A338820 * A338822 A338823 A338824

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Nov 10 2020

Status

approved