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.

A135264 a(n) = 3*A132357(n).

Original entry on oeis.org

3, 12, 42, 123, 366, 1092, 3279, 9840, 29526, 88575, 265722, 797160, 2391483, 7174452, 21523362, 64570083, 193710246, 581130732, 1743392199, 5230176600, 15690529806, 47071589415, 141214768242, 423644304720, 1270932914163
Offset: 0

Views

Author

Paul Curtz, Dec 02 2007

Keywords

Comments

Digital roots yield a hexaperiodic sequence A010888(a(n))= 3*A135265(n+1).

Programs

  • GAP
    a:=[3,12,42,123];; for n in [5..30] do a[n]:=3*a[n-1]-a[n-3]+ 3*a[n-4]; od; a; # G. C. Greubel, Nov 21 2019
  • Magma
    R:=PowerSeriesRing(Integers(), 30); Coefficients(R!( 3*(1+x+2*x^2)/(1-3*x+x^3-3*x^4) )); // G. C. Greubel, Nov 21 2019
    
  • Maple
    seq(coeff(series(3*(1+x+2*x^2)/(1-3*x+x^3-3*x^4), x, n+1), x, n), n = 0..30); # G. C. Greubel, Nov 21 2019
  • Mathematica
    LinearRecurrence[{3,0,-1,3}, {3,12,42,123}, 25] (* G. C. Greubel, Oct 07 2016 *)
  • PARI
    my(x='x+O('x^30)); Vec(3*(1+x+2*x^2)/(1-3*x+x^3-3*x^4)) \\ G. C. Greubel, Nov 21 2019
    
  • Sage
    def A135264_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P(3*(1+x+2*x^2)/(1-3*x+x^3-3*x^4)).list()
    A135264_list(30) # G. C. Greubel, Nov 21 2019
    

Formula

a(n) = 3*a(n-1) - a(n-3) + 3*a(n-4).
G.f.: 3*(1 + x + 2*x^2)/(1 - 3*x + x^3 - 3*x^4). - G. C. Greubel, Oct 07 2016 [corrected by Georg Fischer, May 10 2019]

Extensions

Edited, corrected and extended by R. J. Mathar, Jul 28 2008

A144110 Period 6: repeat [2, 2, 2, 1, 1, 1].

Original entry on oeis.org

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

Views

Author

Philippe Deléham, Sep 11 2008, Sep 15 2008

Keywords

Comments

a(n) = 2 for n = 0,1,2 modulo 6; a(n) = 1 for n = 3,4,5 modulo 6.

Crossrefs

Programs

Formula

G.f.: (1+2*x^3)/((1-x)*(1+x)*(1-x+x^2)); a(n) = 3/2-(-1)^n/6-A057079(n)/3. [R. J. Mathar, Sep 17 2008]
a(n) = a(n-1) - a(n-3) + a(n-4) for n>3; a(n) = 1 + mod(floor((-n-1)/3), 2); a(n) = A088911(n) + 1. - Wesley Ivan Hurt, Sep 04 2014
a(n) = (9 + cos(n*Pi) + 2*cos(n*Pi/3) + 2*sqrt(3)*sin(n*Pi/3))/6. - Wesley Ivan Hurt, Jun 23 2016

A178331 Decimal expansion of (17+2*sqrt(210))/29.

Original entry on oeis.org

1, 5, 8, 5, 6, 1, 2, 1, 8, 9, 3, 9, 2, 3, 7, 5, 0, 7, 4, 0, 4, 9, 5, 6, 3, 0, 4, 5, 3, 2, 2, 0, 5, 3, 2, 2, 2, 2, 8, 5, 5, 2, 6, 4, 0, 5, 1, 5, 5, 7, 9, 1, 2, 4, 7, 4, 9, 6, 2, 7, 0, 6, 7, 6, 3, 5, 2, 9, 7, 5, 4, 7, 3, 9, 7, 6, 1, 1, 5, 8, 9, 1, 1, 5, 2, 5, 9, 0, 5, 6, 4, 9, 6, 5, 7, 6, 6, 7, 2, 3, 9, 8, 2, 9, 6
Offset: 1

Views

Author

Klaus Brockhaus, May 25 2010

Keywords

Comments

Continued fraction expansion of (17+2*sqrt(210))/29 is A135265.

Examples

			(17+2*sqrt(210))/29 = 1.58561218939237507404...
		

Crossrefs

Cf. A176441 (decimal expansion of sqrt(210)), A135265 (repeat 1, 1, 1, 2, 2, 2).

Programs

  • Mathematica
    RealDigits[(17+2Sqrt[210])/29,10,120][[1]] (* Harvey P. Dale, Apr 05 2019 *)
Showing 1-3 of 3 results.