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 1-4 of 4 results.

A093145 Third binomial transform of Fibonacci(3n)/Fibonacci(3).

Original entry on oeis.org

0, 1, 10, 80, 600, 4400, 32000, 232000, 1680000, 12160000, 88000000, 636800000, 4608000000, 33344000000, 241280000000, 1745920000000, 12633600000000, 91417600000000, 661504000000000, 4786688000000000, 34636800000000000
Offset: 0

Views

Author

Paul Barry, Mar 26 2004

Keywords

Comments

Fifth binomial transform of 1,5,5,25,25,125. - Al Hakanson (hawkuu(AT)gmail.com), Jul 13 2009

Crossrefs

Programs

  • Magma
    [n le 2 select n - 1 else 10*Self(n-1)-20*Self(n-2): n in [1..25]]; // Vincenzo Librandi, Dec 30 2012
  • Mathematica
    Join[{a=0,b=1},Table[c=10*b-20*a;a=b;b=c,{n,60}]] (* Vladimir Joseph Stephan Orlovsky, Jan 27 2011 *)
    f[n_] := Block[{s = Sqrt@ 5}, Simplify[((1 + s)(5 + s)^n + (1 - s)(5 - s)^n)/2]]; Array[f, 21, 0] (* Or *)
    a[n_] := 10 a[n - 1] - 20 a[n - 2]; a[0] = 0; a[1] = 1; Array[a, 22, 0] (* Or *)
    CoefficientList[Series[x/(1 - 10 x + 20 x^2), {x, 0, 21}], x] (* Robert G. Wilson v, Mar 07 2011 *)
    LinearRecurrence[{10,-20},{0,1},30] (* Harvey P. Dale, Jan 23 2019 *)
  • Sage
    [lucas_number1(n,10,20) for n in range(0, 21)] # Zerinvary Lajos, Apr 26 2009
    

Formula

G.f.: x/(1 - 10*x + 20*x^2).
a(n) = ((5+sqrt(5))^n - (5-sqrt(5))^n)/(2*sqrt(5)).
a(n) = Sum_{k=0..n} binomial(n, 2*k+ 1)*5^(n-k-1).
a(n) = 10*a(n-1) - 20*a(n-2), n > 1; a(0)=0, a(1)=1. - Zerinvary Lajos, Apr 26 2009
G.f.: A(x) = x*G(0)/(1-5*x) where G(k) = 1 + 5*x/(1-5*x - x*(1-5*x)/(x + (1-5*x)/G(k+1) )); (recursively defined continued fraction). - Sergei N. Gladkovskii, Dec 30 2012

A108404 Expansion of (1-4x)/(1-8x+11x^2).

Original entry on oeis.org

1, 4, 21, 124, 761, 4724, 29421, 183404, 1143601, 7131364, 44471301, 277325404, 1729418921, 10784771924, 67254567261, 419404046924, 2615432135521, 16310012568004, 101710347053301, 634272638178364, 3955367287840601
Offset: 0

Views

Author

Philippe Deléham, Jul 04 2005

Keywords

Comments

Binomial transform of A098648. Second binomial transform of A001077. Third binomial transform of A084057. 4th binomial transform of (1, 0, 5, 0, 25, 0, 125, 0, 625, 0, 3125, ...).

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[(1-4x)/(1-8x+11x^2),{x,0,30}],x] (* or *) LinearRecurrence[{8,-11},{1,4},30] (* Harvey P. Dale, Jan 03 2012 *)

Formula

E.g.f.: exp(4x)cosh(sqrt(5)x).
a(n) = 8a(n-1) - 11a(n-2), a(0) = 1, a(1) = 4.
a(n) = ((4+sqrt(5))^n + (4-sqrt(5))^n)/2.
a(n+1)/a(n) converges to 4 + sqrt(5) = 6.2360679774997896964... = 4+A002163.
a(n) = A091870(n+1)-4*A091870(n). - R. J. Mathar, Nov 10 2013

A292466 Triangle read by rows: T(n,k) = 4*T(n-1,k-1) + T(n,k-1) with T(2*m,0) = 0 and T(2*m+1,0) = 5^m.

Original entry on oeis.org

0, 1, 1, 0, 4, 8, 5, 5, 21, 53, 0, 20, 40, 124, 336, 25, 25, 105, 265, 761, 2105, 0, 100, 200, 620, 1680, 4724, 13144, 125, 125, 525, 1325, 3805, 10525, 29421, 81997, 0, 500, 1000, 3100, 8400, 23620, 65720, 183404, 511392, 625, 625, 2625, 6625, 19025, 52625
Offset: 0

Views

Author

Seiichi Manyama, Sep 22 2017

Keywords

Examples

			First few rows are:
    0;
    1,   1;
    0,   4,   8;
    5,   5,  21,   53;
    0,  20,  40,  124,  336;
   25,  25, 105,  265,  761,  2105;
    0, 100, 200,  620, 1680,  4724, 13144;
  125, 125, 525, 1325, 3805, 10525, 29421, 81997.
--------------------------------------------------------------
The diagonal is      {0, 1,  8,  53, 336, 2105, ...} and
the next diagonal is {1, 4, 21, 124, 761, 4724, ...}.
Two sequences have the following property:
     1^2 - 5*   0^2 = 1      (= 11^0),
     4^2 - 5*   1^2 = 11     (= 11^1),
    21^2 - 5*   8^2 = 121    (= 11^2),
   124^2 - 5*  53^2 = 1331   (= 11^3),
   761^2 - 5* 336^2 = 14641  (= 11^4),
  4724^2 - 5*2105^2 = 161051 (= 11^5),
  ...
		

Crossrefs

The diagonal of the triangle is A091870.
The next diagonal of the triangle is A108404.
T(n,k) = b*T(n-1,k-1) + T(n,k-1): A292789 (b=-3), A292495 (b=-2), A117918 and A228405 (b=1), A227418 (b=2), this sequence (b=4).

Formula

T(n+1,n)^2 - 5*T(n,n)^2 = 11^n.

A162769 a(n) = ((1+sqrt(5))*(4+sqrt(5))^n + (1-sqrt(5))*(4-sqrt(5))^n)/2.

Original entry on oeis.org

1, 9, 61, 389, 2441, 15249, 95141, 593389, 3700561, 23077209, 143911501, 897442709, 5596515161, 34900251489, 217640345141, 1357219994749, 8463716161441, 52780309349289, 329141597018461, 2052549373305509
Offset: 0

Views

Author

Al Hakanson (hawkuu(AT)gmail.com), Jul 13 2009

Keywords

Comments

Binomial transform of A082762. Fourth binomial transform of A162962. Inverse binomial transform of A093145 without initial 0.

Crossrefs

Programs

  • Magma
    Z:=PolynomialRing(Integers()); N:=NumberField(x^2-5); S:=[ ((1+r)*(4+r)^n+(1-r)*(4-r)^n)/2: n in [0..19] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Jul 19 2009
  • Mathematica
    f[n_] := Block[{s = Sqrt@ 5}, Simplify[((1 + s)(4 + s)^n + (1 - s)(4 - s)^n)/2]]; Array[f, 21, 0] (* Or *)
    a[n_] := 8 a[n - 1] - 11 a[n - 2]; a[0] = 1; a[1] = 9; Array[a, 22, 0] (* Or *)
    CoefficientList[Series[(1 + x)/(1 - 8 x + 11 x^2), {x, 0, 21}], x] (* Robert G. Wilson v *)

Formula

a(n) = 8*a(n-1) - 11*a(n-2) for n > 1; a(0) = 1, a(1) = 9.
G.f.: (1+x)/(1-8*x+11*x^2).
a(n) = A091870(n)+A091870(n+1). - R. J. Mathar, Feb 04 2021

Extensions

Edited and extended beyond a(5) by Klaus Brockhaus, Jul 19 2009
Showing 1-4 of 4 results.