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 1-2 of 2 results.

A134667 Period 6: repeat [0, 1, 0, 0, 0, -1].

Original entry on oeis.org

0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0
Offset: 0

Views

Author

Paul Curtz, Jan 26 2008

Keywords

Comments

Dirichlet series for the non-principal character modulo 6: L(s,chi) = Sum_{n>=1} a(n)/n^s. For example L(1,chi) = A093766, L(2,chi) = A214552, and L(3,chi) = Pi^3/(18*sqrt(3)). See Jolley eq. (314) and arXiv:1008.2547 L(m=6,r=2,s). - R. J. Mathar, Jul 31 2010

Examples

			G.f. = x - x^5 + x^7 - x^11 + x^13 - x^17 + x^19 - x^23 + x^25 - x^29 + ...
		

References

  • T. M. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, 1986, page 139, k=6, Chi_2(n).
  • L. B. W. Jolley, Summation of Series, Dover (1961).

Crossrefs

Programs

  • Magma
    &cat[[0, 1, 0, 0, 0, -1]^^20]; // Wesley Ivan Hurt, Jun 20 2016
  • Maple
    A134667:=n->[0, 1, 0, 0, 0, -1][(n mod 6)+1]: seq(A134667(n), n=0..100);
    # Wesley Ivan Hurt, Jun 20 2016
  • Mathematica
    a[ n_] := JacobiSymbol[-12, n]; (* Michael Somos, Apr 24 2014 *)
    a[ n_] := {1, 0, 0, 0, -1, 0}[[Mod[n, 6, 1]]]; (* Michael Somos, Apr 24 2014 *)
    PadRight[{},120,{0,1,0,0,0,-1}] (* Harvey P. Dale, Aug 01 2021 *)
  • PARI
    {a(n) = [0, 1, 0, 0, 0, -1][n%6+1]}; /* Michael Somos, Feb 10 2008 */
    
  • PARI
    {a(n) = kronecker(-12, n)}; /* Michael Somos, Feb 10 2008 */
    
  • PARI
    {a(n) = if( n < 0, -a(-n), if( n<1, 0, direuler(p=2, n, 1 / (1 - kronecker(-12, p) * X))[n]))}; /* Michael Somos, Aug 11 2009 */
    

Formula

Euler transform of length 6 sequence [0, 0, 0, -1, 0, 1]. - Michael Somos, Feb 10 2008
G.f.: x * (1 - x^4) / (1 - x^6) = x*(1+x^2) / (1 + x^2 + x^4) = x*(1+x^2) / ( (1+x+x^2)*(x^2-x+1) ).
G.f. A(x) satisfies 0 = f(A(x), A(x^2), A(x^3)) where f(u, v, w) = w * (2 + v - u^2 - 2*v^2) - 2 * u * v. - Michael Somos, Aug 11 2009
a(n) is multiplicative with a(p^e) = 0^e if p = 2 or p = 3, a(p^e) = 1 if p == 1 (mod 6), a(p^e) = (-1)^e if p == 5 (mod 6). - Michael Somos, Aug 11 2009
a(-n) = -a(n). a(n+6) = a(n). a(2*n) = a(3*n) = 0.
sqrt(3)*a(n) = sin(Pi*n/3) + sin(2*Pi*n/3). - R. J. Mathar, Oct 08 2011
a(n) + a(n-2) + a(n-4) = 0 for n>3. - Wesley Ivan Hurt, Jun 20 2016
E.g.f.: 2*sin(sqrt(3)*x/2)*cosh(x/2)/sqrt(3). - Ilya Gutkovskiy, Jun 21 2016

A100286 Expansion of (1+2*x^2-2*x^3+2*x^4)/(1-x+x^2-x^3+x^4-x^5).

Original entry on oeis.org

1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2, 1, 1, 2, 0, 0, 2
Offset: 0

Views

Author

Paul Barry, Nov 11 2004

Keywords

Comments

Period 6: repeat [1,1,2,0,0,2]. - G. C. Greubel, Feb 06 2023
Decimal expansion of 3394/30303. - Elmo R. Oliveira, May 11 2024

Crossrefs

Programs

  • Magma
    [2 +(n mod 2)*(1-((n+2) mod 3)) -((n+1) mod 3): n in [0..100]]; // G. C. Greubel, Feb 06 2023
    
  • Mathematica
    CoefficientList[Series[(1+2x^2-2x^3+2x^4)/(1-x+x^2-x^3+x^4-x^5),{x,0,100}],x] (* Harvey P. Dale, Mar 03 2019 *)
    PadRight[{}, 120, {1,1,2,0,0,2}] (* G. C. Greubel, Feb 06 2023 *)
  • SageMath
    def A100286(n): return 2 +(n%2)*(1-((n-1)%3)) -((n+1)%3)
    [A100286(n) for n in range(101)] # G. C. Greubel, Feb 06 2023

Formula

a(n) = a(n-1) - a(n-2) + a(n-3) - a(n-4) + a(n-5).
a(n) = (1/6)*(6 + 3*cos(Pi*n/3) - 3*cos(2*Pi*n/3) + sqrt(3)*sin(Pi*n/3) - 3*sqrt(3)*sin(2*Pi*n/3)).
a(n) = mod(A100284(n), 3).
From G. C. Greubel, Feb 06 2023: (Start)
a(n) = a(n-6).
a(n) = (1/2)*(2 + A010892(n) - A049347(n) - 2*A049347(n-1)).
a(n) = 2 + (n mod 2)*(1 - (n-1 mod 3)) - (n+1 mod 3). (End)
a(n) = 1 + A131736(n). - Elmo R. Oliveira, Jun 20 2024
Showing 1-2 of 2 results.