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.

Showing 1-3 of 3 results.

A374190 Complement of A374189 in A005843.

Original entry on oeis.org

0, 4, 6, 8, 14, 16, 20, 22, 30, 32, 36, 38, 40, 46, 52, 54, 62, 64, 68, 70, 72, 78, 80, 84, 86, 94, 100, 102, 104, 110, 116, 118, 126, 128, 132, 134, 136, 142, 144, 148, 150, 158, 160, 164, 166, 168, 174, 180, 182, 190, 196, 198, 200, 206, 208, 212, 214, 222
Offset: 1

Views

Author

Peter Luschny, Jul 02 2024

Keywords

Comments

k is a term if and only if for all a of the form 4*n - 1 (n>=1) there is an even k such that K(a / k) = K((-1)^floor(k/2)*k / a), where K denotes the Kronecker symbol (A372728).

Crossrefs

Cf. A374189, A005843 (even numbers).

A374188 Array read by ascending antidiagonals: b is a term of row A(a) if and only if K(a/b) != K(A374157(b)/a), where K denotes the Kronecker symbol (A372728), and a = 4*n - 1 for some n >= 1.

Original entry on oeis.org

2, 2, 10, 2, 10, 26, 2, 10, 12, 28, 2, 26, 12, 18, 34, 2, 10, 28, 18, 24, 44, 2, 10, 12, 34, 24, 26, 50, 2, 10, 12, 18, 44, 26, 34, 56, 2, 10, 26, 18, 24, 56, 28, 44, 58, 2, 12, 12, 28, 24, 26, 58, 34, 48, 74, 2, 10, 18, 18, 34, 26, 28, 74, 42, 50, 76
Offset: 1

Views

Author

Peter Luschny, Jun 30 2024

Keywords

Comments

We say two integers, a and b, are related by the golden theorem (Gauss) if K(a/b) = K(A374157(b)/a), an identity, that is valid for all whole numbers a (A001057) and all odd numbers b (A005408). This fact is equivalent to the law of quadratic reciprocity and its first and second supplement. See A372728 (Kronecker) and A373223 (Gauss) for details and examples. Here, we complement this by looking at pairs of integers that do not obey this law.

Examples

			  [n] [ a] b ...
  [1] [ 3] 2, 10, 26, 28, 34, 44, 50, 56, 58, 74, 76, 82, ...  A374180
  [2] [ 7] 2, 10, 12, 18, 24, 26, 34, 44, 48, 50, 58, 60, ...  A374181
  [3] [11] 2, 10, 12, 18, 24, 26, 28, 34, 42, 48, 50, 56, ...  A374182
  [4] [15] 2, 26, 28, 34, 44, 56, 58, 74, 76, 82, 88, 92, ...  A374183
  [5] [19] 2, 10, 12, 18, 24, 26, 28, 34, 42, 44, 48, 50, ...  A374184
  [6] [23] 2, 10, 12, 18, 24, 26, 28, 34, 42, 44, 48, 50, ...
  [7] [27] 2, 10, 26, 28, 34, 44, 50, 56, 58, 74, 76, 82, ...
  [8] [31] 2, 10, 12, 18, 24, 26, 28, 34, 42, 44, 48, 50, ...
		

Crossrefs

Rows: A374180 [1], A374181 [2], A374182 [3], A374183 [4], A374184 [5].
Cf. A374189 (seen as set), A372728 (Kronecker), A373223 (Gauss), A374157, A004767.

Programs

  • Maple
    KS := (a, n) -> NumberTheory:-KroneckerSymbol(a, n):
    A374157 := n -> ifelse(iquo(n, 2)::even, n, -n):
    A374188_row := (a, len) -> local n; select(n -> (KS(a, n) <> KS(A374157(n), a)), [seq(0..len)]): seq(print(A374188_row(4*m - 1, 350)), m = 1..5);
  • SageMath
    def A374157(n): return (-1)**(n // 2)*n
    def ks(a, n): return kronecker_symbol(a, n)
    def ksp(a, len): return [n for n in range(len) if ks(a, n) != ks(A374157(n), a)]
    def A374188_row(n, len): return ksp(4*n - 1, len)
    for m in range(1, 8): print(A374188_row(m, 100)[:12])

Formula

All terms are even.

A374187 Least a of the form 4*n - 1 (n>=1) such that there is a positive integer k so that K(a / k) != K((-1)^floor(k/2)*k / a), where K denotes the Kronecker symbol (A372728).

Original entry on oeis.org

3, 3, 7, 7, 7, 3, 3, 3, 11, 3, 7, 3, 3, 3, 7, 7, 3, 3, 3, 3, 7, 3, 7, 3, 3, 7, 3, 7, 7, 3, 3, 3, 7, 3, 3, 3, 3, 7, 7, 3, 3, 3, 3, 3, 7, 3, 7, 3, 3, 7, 11, 7, 3, 3, 3, 3, 7, 3, 7, 3, 3, 3, 11, 7, 3, 3, 3, 3, 7, 3, 3, 3, 7, 3, 7, 7, 3, 3, 3, 7, 3, 3, 3, 3, 7, 3
Offset: 1

Views

Author

Peter Luschny, Jul 02 2024

Keywords

Comments

These values witness the correctness of A374189. They seem to grow very slowly.

Crossrefs

Showing 1-3 of 3 results.