OFFSET
1,1
COMMENTS
Numbers so far are all congruent to 7 (mod 24). - Ralf Stephan, Jul 07 2003
REFERENCES
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
D. H. Lehmer, E. Lehmer and D. Shanks, Integer sequences having prescribed quadratic character, Math. Comp., 24 (1970), 433-451.
D. H. Lehmer, E. Lehmer and D. Shanks, Integer sequences having prescribed quadratic character, Math. Comp., 24 (1970), 433-451 [Annotated scanned copy]
PROG
(PARI) isok(p, oddpn) = {forprime(q=3, oddpn, if (kronecker(p, q) != -kronecker(-1, q), return (0)); ); return (1); }
a(n) = {oddpn = prime(n+1); forprime(p=3, , if ((p%8) == 7, if (isok(p, oddpn), return (p)); ); ); } \\ Michel Marcus, Oct 18 2017
(Python)
from sympy import legendre_symbol as L, primerange, prime, nextprime
def isok(p, oddpn):
for q in primerange(3, oddpn + 1):
if L(p, q)!=-L(-1, q): return 0
return 1
def a(n):
oddpn=prime(n + 1)
p=3
while True:
if p%8==7:
if isok(p, oddpn): return p
p=nextprime(p) # Indranil Ghosh, Oct 23 2017, after PARI code by Michel Marcus
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Better name and more terms from Sean A. Irvine, Mar 06 2013
Name and offset corrected by Michel Marcus, Oct 18 2017
STATUS
approved