cp's OEIS Frontend

Maple

# Returned values of -1 indicate that either a(n) = 0 or a(n) > 10^1000.
f:= proc(n) local m,x,y,S,cf,i,c,a,b,A,M,Sp;
  m:= n+1;
  if issqr(m) then
    S:= [isolve(x^2+n=m*y^2)];
    S:= map(t -> subs(t,[x,y]),S);
    S:= select(t -> andmap(isprime,t),S);
    if S = [] then return 0
    else return min(map(t -> t[1],S))
    fi;
  fi;
  cf:= NumberTheory:-ContinuedFraction(sqrt(m));
  for i from 1 do
    c:= Convergent(cf,i);
    if numer(c)^2 - m*denom(c)^2 = 1 then break fi
  od;
  a:= numer(c); b:= denom(c);
  A:= <|>;
  M:= floor(sqrt(n)*(1+sqrt(a+b*sqrt(m)))/(2*sqrt(m)));
  S:= select(t -> issqr(m*t^2-m+1), [$0..M]);
  S:= select(t -> igcd(t[1],t[2])=1,map(t -> , S));
  S:= map(t -> (t, <-t[1],t[2]>), S);
  if nops(S) = 0 then return 0 fi;
  for i from 0 do
    Sp:= select(t -> isprime(t[1]) and isprime(t[2]),S);
    if nops(Sp)>0 then return min(map(t -> t[1],Sp)) fi;
    S:= map(t -> A.t,S);
    if min(map(t -> t[1],S))>10^1000 then break fi;
  od;
  -1
end proc:
map(f, [$1..20]);