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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A168061 Denominator of (n+3) / ((n+2) * (n+1) * n).

Original entry on oeis.org

3, 24, 10, 120, 105, 112, 252, 720, 165, 1320, 858, 728, 1365, 3360, 680, 4896, 2907, 2280, 3990, 9240, 1771, 12144, 6900, 5200, 8775, 19656, 3654, 24360, 13485, 9920, 16368, 35904, 6545, 42840, 23310, 16872, 27417, 59280, 10660, 68880, 37023, 26488, 42570
Offset: 1

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Author

Keywords

Comments

Numerator of ((n+3)/(n+2)/(n+1)/n) = A060789(n).

Crossrefs

Cf. A060789.

Programs

  • GAP
    List([1..10^3],n->DenominatorRat((n+3)/(n+2)/(n+1)/n)); # Muniru A Asiru, Feb 04 2018
  • Maple
    seq(denom((n+3)/(n+2)/(n+1)/n), n=1..10^3); # Muniru A Asiru, Feb 04 2018
  • Mathematica
    Table[Denominator[(n+3)/(n+2)/(n+1)/n],{n,60}]
    LinearRecurrence[{0,0,0,0,0,4,0,0,0,0,0,-6,0,0,0,0,0,4,0,0,0,0,0,-1},{3,24,10,120,105,112,252,720,165,1320,858,728,1365,3360,680,4896,2907,2280,3990,9240,1771,12144,6900,5200},50] (* Harvey P. Dale, Apr 06 2017 *)
  • PARI
    vector(50, n, denominator(((n+3)/(n+2)/(n+1)/n))) \\ Colin Barker, Feb 04 2018
    
  • PARI
    Vec(x*(3 + 24*x + 10*x^2 + 120*x^3 + 105*x^4 + 112*x^5 + 240*x^6 + 624*x^7 + 125*x^8 + 840*x^9 + 438*x^10 + 280*x^11 + 375*x^12 + 624*x^13 + 80*x^14 + 336*x^15 + 105*x^16 + 40*x^17 + 30*x^18 + 24*x^19 + x^20) / ((1 - x)^4*(1 + x)^4*(1 - x + x^2)^4*(1 + x + x^2)^4) + O(x^60)) \\ Colin Barker, Feb 04 2018
    

Formula

a(n) = 4*a(n-6) -6*a(n-12) +4*a(n-18) -a(n-24) = A007531(n+2)/A089145(n). - R. J. Mathar, Nov 18 2009
G.f.: x*(3 + 24*x + 10*x^2 + 120*x^3 + 105*x^4 + 112*x^5 + 240*x^6 + 624*x^7 + 125*x^8 + 840*x^9 + 438*x^10 + 280*x^11 + 375*x^12 + 624*x^13 + 80*x^14 + 336*x^15 + 105*x^16 + 40*x^17 + 30*x^18 + 24*x^19 + x^20) / ((1 - x)^4*(1 + x)^4*(1 - x + x^2)^4*(1 + x + x^2)^4). - Colin Barker, Feb 04 2018

A306764 a(n) is a sequence of period 12: repeat [1, 1, 6, 2, 1, 3, 2, 2, 3, 1, 2, 6].

Original entry on oeis.org

1, 1, 6, 2, 1, 3, 2, 2, 3, 1, 2, 6, 1, 1, 6, 2, 1, 3, 2, 2, 3, 1, 2, 6, 1, 1, 6, 2, 1, 3, 2, 2, 3, 1, 2, 6, 1, 1, 6, 2, 1, 3, 2, 2, 3, 1, 2, 6, 1, 1, 6, 2, 1, 3, 2, 2, 3, 1, 2, 6, 1, 1, 6, 2, 1, 3, 2, 2, 3, 1, 2, 6
Offset: 0

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Author

Paul Curtz, Mar 08 2019

Keywords

Comments

a(1) to a(12) is a palindrome.
A089145(n) = A089128(n+3).
A089128(n) = A089145(n+3).
a(1) + a(2) + a(3) + a(4) = a(5) + a(6) + a(7) + a(8) = a(9) + a(10) + a(11) + a(12) = 10.

Examples

			a(0) =  6/6  = 1;
a(1) = 10/10 = 1;
a(2) = 30/5  = 6;
a(3) = 42/21 = 2.
		

Crossrefs

Cf. A064038, A089128 and A089145 (shifted bisections), A306368, A010692.

Programs

  • Mathematica
    PadRight[{},120,{1,1,6,2,1,3,2,2,3,1,2,6}] (* or *) LinearRecurrence[ {0,0,1,0,0,-1,0,0,1},{1,1,6,2,1,3,2,2,3},120] (* Harvey P. Dale, Dec 16 2021 *)
  • PARI
    Vec((1 + x + 6*x^2 + x^3 - 3*x^5 + x^6 + 2*x^7 + 6*x^8) / ((1 - x)*(1 + x^2)*(1 + x + x^2)*(1 - x^2 + x^4)) + O(x^80)) \\ Colin Barker, Dec 11 2019

Formula

a(n) = 2*A064038(n+3)/A306368(n).
a(n) = interleave A089128(n-1), A089128(n+1).
a(n) = interleave A089145(n+2), A089145(n-2).
From Colin Barker, Dec 09 2019: (Start)
G.f.: (1 + x + 6*x^2 + x^3 - 3*x^5 + x^6 + 2*x^7 + 6*x^8) / ((1 - x)*(1 + x^2)*(1 + x + x^2)*(1 - x^2 + x^4)).
a(n) = a(n-3) - a(n-6) + a(n-9) for n>8.
(End)
Showing 1-2 of 2 results.