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.

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A293654 Integers not represented by cyclotomic binary forms.

Original entry on oeis.org

1, 2, 6, 14, 15, 22, 23, 24, 30, 33, 35, 38, 42, 44, 46, 47, 51, 54, 56, 59, 60, 62, 66, 69, 70, 71, 77, 78, 83, 86, 87, 88, 92, 94, 95, 96, 99, 102, 105, 107, 110, 114, 115, 118, 119, 120, 123, 126, 131, 132, 134, 135, 138, 140, 141, 142, 143, 150
Offset: 1

Views

Author

Michel Waldschmidt, Feb 16 2018

Keywords

Comments

Possibly a supersequence of A055039. - C. S. Davis, May 10 2025

Crossrefs

Complement of A296095.
For n>2, subsequence of A383785, following from Proposition 6.2 of Fouvry et al.

Programs

  • Maple
    g := 1;
    for m from 1 to 1000 do
        for n from 3 to 50 do
            for x from -50 to 50 do
                for y from -50 to 50 do
                    if (F[n] = m, max(abs(x), abs(y)) > 1
                    then r[g] := m; m := m+1; n := 3;
                         x := -50; y := -50; g := g+1
                    fi;
    od; od; od; od;
    for t to 519 do print(r[{t}] = r[t]) od;
    s[1] := 1; s[2] := 2; g := 2;
    for i from 1 to 518 do
        for j from r[i]+1 to r[i+1]-1 do
            g := g+1; s[g] := j
    od; od;
    for t to 481 do s[t] od;
  • Mathematica
    isA296095[n_] := If[n<3, Return[False], logn = Log[n]^1.161; K = Floor[ 5.383*logn]; M = Floor[2*(n/3)^(1/2)]; k = 3; While[True, If[k == 7, K = Ceiling[4.864*logn]; M = Ceiling[2*(n/11)^(1/4)]]; For[y = 2, y <= M, y++, p[z_] = y^EulerPhi[k]*Cyclotomic[k, z]; For[x = 1, x <= y, x++, If[n == p[x/y], Return[True]]]]; k++; If[k>K, Break[]]]; Return[False]];
    Select[Range[150], !isA296095[#]&] (* Jean-François Alcover, Jun 21 2018, after Peter Luschny *)
  • Sage
    def A293654list(upto):
        return [n for n in (1..upto) if not isA296095(n)]
    print(A293654list(150)) # Peter Luschny, Feb 25 2018

A383784 Norms of vectors in any regular planar tiling (square or A2 lattice).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 7, 8, 9, 10, 12, 13, 16, 17, 18, 19, 20, 21, 25, 26, 27, 28, 29, 31, 32, 34, 36, 37, 39, 40, 41, 43, 45, 48, 49, 50, 52, 53, 57, 58, 61, 63, 64, 65, 67, 68, 72, 73, 74, 75, 76, 79, 80, 81, 82, 84, 85, 89, 90, 91, 93, 97, 98, 100, 101, 103, 104
Offset: 1

Views

Author

C. S. Davis, May 09 2025

Keywords

Crossrefs

Union of A001481 and A003136.
Complement of A383785.
Subsequence of A000401.
Showing 1-2 of 2 results.