The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A329095 Odd numbers k such that x^2 == 2 (mod k) has no solution. 2
 3, 5, 9, 11, 13, 15, 19, 21, 25, 27, 29, 33, 35, 37, 39, 43, 45, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 75, 77, 81, 83, 85, 87, 91, 93, 95, 99, 101, 105, 107, 109, 111, 115, 117, 121, 123, 125, 129, 131, 133, 135, 139, 141, 143, 145, 147, 149, 153, 155, 157, 159, 163 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Complement of A058529 over the odd numbers: odd numbers k such that x^2 == 2 (mod k) has solutions. Odd numbers k such that at least one prime factor of k is congruent to 3 or 5 modulo 8 (at least one prime factor is in A003629). Also odd terms in A025020. LINKS Robert Israel, Table of n, a(n) for n = 1..10000 EXAMPLE x^2 == 2 (mod 45) has no solution, so 45 is a term. MAPLE filter:= proc(t) (numtheory:-factorset(t) mod 8) intersect {3, 5} <> {} end proc: select(filter, [seq(i, i=1..1000, 2)]); # Robert Israel, Nov 05 2019 MATHEMATICA Reap[Do[If[AnyTrue[FactorInteger[k][[All, 1]], MatchQ[Mod[#, 8], 3|5]&], Sow[k]], {k, 1, 999, 2}]][[2, 1]] (* Jean-François Alcover, Aug 22 2020 *) PROG (PARI) isA329095(k) = (k%2) && !issquare(Mod(2, k)) CROSSREFS Cf. A003629. A047621 is a subsequence. Cf. A058529, A057126, A025020 (numbers k such that x^2 == 2 (mod k) has no solution). Sequence in context: A325129 A173263 A285141 * A319009 A294427 A141231 Adjacent sequences:  A329092 A329093 A329094 * A329096 A329097 A329098 KEYWORD nonn,easy AUTHOR Jianing Song, Nov 04 2019 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 12 10:54 EDT 2021. Contains 343821 sequences. (Running on oeis4.)