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A025023
Numbers whose least quadratic nonresidue (A020649) is 7.
10
71, 142, 191, 239, 241, 359, 382, 409, 431, 478, 482, 599, 601, 718, 769, 818, 862, 911, 1031, 1198, 1202, 1249, 1321, 1439, 1489, 1538, 1609, 1822, 1871, 2039, 2062, 2089, 2111, 2161, 2281, 2498, 2591, 2642, 2711, 2878, 2879, 2978, 3001, 3119, 3121, 3169
OFFSET
1,1
LINKS
Eric Weisstein's World of Mathematics, Quadratic Nonresidue.
MATHEMATICA
Select[Range[3200], Min @ Complement[Range[# - 1], Mod[Range[#/2]^2, #]] == 7 &] (* Amiram Eldar, Oct 31 2020 *)
PROG
(PARI) residue(n, m)=local(r); r=0; for(i=1, floor(m/2), if(i^2%m==n, r=1)); r
isA025023(n)=residue(2, n) && residue(3, n) && residue(5, n) && !residue(7, n) \\ Michael B. Porter, Apr 19 2010
(PARI) is(n)=issquare(Mod(2, n)) && issquare(Mod(3, n)) && issquare(Mod(5, n)) && !issquare(Mod(7, n)) \\ Charles R Greathouse IV, Jan 24 2020
KEYWORD
nonn
STATUS
approved