cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A025020 Numbers whose least quadratic nonresidue (A020649) is 2.

Original entry on oeis.org

3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 15, 16, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 32, 33, 35, 36, 37, 38, 39, 40, 42, 43, 44, 45, 48, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 63, 64, 65, 66, 67, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 83, 84, 85, 86, 87, 88, 90, 91, 92
Offset: 1

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Programs

  • Mathematica
    Select[Range[100], Min @ Complement[Range[# - 1], Mod[Range[#/2]^2, #]] == 2 &] (* Amiram Eldar, Oct 31 2020 *)
  • PARI
    isA025020(n)={local(r);r=1;for(m=1,n-1,if(m^2%n==2,r=0));r} \\ Michael B. Porter, Apr 16 2010