A376999 a(n) is the least number k that is a quadratic residue modulo prime(n) but is a quadratic nonresidue modulo all previous odd primes.

0, 5, 2, 38, 17, 83, 362, 167, 227, 2273, 398, 5297, 64382, 69467, 116387, 238262, 214037, 430022, 5472953, 9481097, 8062073, 41941577, 86374763, 312521282

Offset: 2

Author

Robert Israel, Oct 20 2024

Keywords

• nonn

Examples

			a(5) = 38 because 38 is a quadratic residue modulo prime(5) = 11 but is not a quadratic residue modulo the previous odd primes 3, 5 and 7, and no number smaller than 38 works.
		

Crossrefs

Cf. A377212.

Programs

Maple

f:= proc(n) local k,p;
  p:= 2;
  for k from 2 do
      p:= nextprime(p);
      if numtheory:-quadres(n,p) = 1 then return k fi
  od
end proc:
V:= Array(2..25): count:= 0:
for k from 2 while count < 24 do
  v:= f(k);
if v > 0 and v <= 25 and V[v] = 0 then
  V[v]:= k; count:= count+1;
fi;
od:
V[2]:= 0:
convert(V,list);