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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A317408 a(n) = n * Fibonacci(2n).

Original entry on oeis.org

0, 1, 6, 24, 84, 275, 864, 2639, 7896, 23256, 67650, 194821, 556416, 1578109, 4449354, 12480600, 34852944, 96949079, 268746336, 742675211, 2046683100, 5626200216, 15430992126, 42235173769, 115380647424, 314656725625, 856733282574, 2329224424344, 6323840144076
Offset: 0

Views

Author

Rigoberto Florez, Jul 27 2018

Keywords

Comments

Derivative of Morgan-Voyce Lucas-type evaluated at 1.

Crossrefs

Programs

  • Maple
    a:= n-> (<<0|1|0|0>, <0|0|1|0>, <0|0|0|1>, <-1|6|-11|6>>^n. <<0, 1, 6, 24>>)[1$2]:
    seq(a(n), n=1..35);  # Alois P. Heinz, Jul 27 2018
  • Mathematica
    CoefficientList[Series[-(x - 1) (x + 1) x/(x^2 - 3 x + 1)^2, {x, 0, 28}], x] (* or *)
    LinearRecurrence[{6, -11, 6, -1}, {0, 1, 6, 24}, 29] (* or *)
    Array[# Fibonacci[2 #] &, 29, 0] (* Michael De Vlieger, Jul 27 2018 *)
  • PARI
    a(n)=n*fibonacci(2*n) \\ Andrew Howroyd, Jul 27 2018
    
  • PARI
    Vec(-(x-1)*(x+1)*x/(x^2-3*x+1)^2 + O(x^30)) \\ Andrew Howroyd, Jul 27 2018

Formula

G.f.: -(x-1)*(x+1)*x/(x^2-3*x+1)^2. - Alois P. Heinz, Jul 27 2018
a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3) - a(n-4) for n > 4. - Andrew Howroyd, Jul 27 2018
a(n) = (2^(-n)*((-(3-sqrt(5))^n + (3+sqrt(5))^n)*n))/sqrt(5). - Colin Barker, Jul 28 2018
a(n) = n*A001906(n). - Omar E. Pol, Jul 29 2018

A094588 a(n) = n*F(n-1) + F(n), where F = A000045.

Original entry on oeis.org

0, 1, 3, 5, 11, 20, 38, 69, 125, 223, 395, 694, 1212, 2105, 3639, 6265, 10747, 18376, 31330, 53277, 90385, 153011, 258523, 436010, 734136, 1234225, 2072043, 3474029, 5817515, 9730748, 16258910, 27139509, 45258917, 75408775, 125538539
Offset: 0

Views

Author

Paul Barry, May 13 2004

Keywords

Comments

This is the transform of the Fibonacci numbers under the inverse of the signed permutations matrix (see A094587).

Crossrefs

Programs

  • Haskell
    a094588 n = a094588_list !! n
    a094588_list = 0 : zipWith (+) (tail a000045_list)
                                   (zipWith (*) [1..] a000045_list)
    -- Reinhard Zumkeller, Mar 04 2012
    
  • Julia
    # The function 'fibrec' is defined in A354044.
    function A094588(n)
        n == 0 && return BigInt(0)
        a, b = fibrec(n - 1)
        a*n + b
    end
    println([A094588(n) for n in 0:34]) # Peter Luschny, May 16 2022
  • Magma
    [n*Fibonacci(n-1)+Fibonacci(n): n in [0..60]]; // Vincenzo Librandi, Apr 23 2011
    
  • Mathematica
    CoefficientList[Series[x (1+x-2x^2)/(1-x-x^2)^2,{x,0,40}],x]  (* Harvey P. Dale, Apr 16 2011 *)
  • PARI
    Vec((1+x-2*x^2)/(1-x-x^2)^2+O(x^99)) \\ Charles R Greathouse IV, Mar 04 2012
    

Formula

G.f. : x*(1 + x - 2*x^2)/(1 - x - x^2)^2.
a(n) = A101220(n, 0, n) - Ross La Haye, Jan 28 2005
a(n) = A109754(n, n). - Ross La Haye, Aug 20 2005
a(n) = (sin(c*n)*i - n*sin(c*(n - 1)))/(i^n*sqrt(5/4)) where c = arccos(i/2). - Peter Luschny, May 16 2022

A136376 a(n) = n*F(n) + (n-1)*F(n-1).

Original entry on oeis.org

1, 3, 8, 18, 37, 73, 139, 259, 474, 856, 1529, 2707, 4757, 8307, 14428, 24942, 42941, 73661, 125951, 214739, 365166, 619508, 1048753, 1771943, 2988457, 5031843, 8459504, 14201994, 23811349, 39873841, 66695539, 111440227, 186016962
Offset: 1

Views

Author

Gary W. Adamson, Dec 28 2007

Keywords

Comments

For n>2, mod 2 = (0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, ...), i.e., two evens followed by four odds (repeating).
Inverse binomial transform of A117202: (1, 4, 15, 52, ...). - Gary W. Adamson, Sep 03 2008

Examples

			a(5) = 37 = a(n)*F(n) + (n-1)*F(n-1) = 5*5 + 4*3 = 25 + 12.
		

Crossrefs

Programs

  • Mathematica
    Table[n*Fibonacci[n] + (n - 1)*Fibonacci[n - 1], {n, 1, 50}] (* Stefan Steinerberger, Dec 28 2007 *)
  • PARI
    a(n)=n*fibonacci(n)+(n-1)*fibonacci(n-1) \\ Charles R Greathouse IV, Oct 07 2015
    
  • PARI
    Vec(x*(1+x)*(1+x^2)/(x^2+x-1)^2 + O(x^100)) \\ Altug Alkan, Oct 28 2015

Formula

a(n) = n*F(n) + (n-1)*F(n-1). Equals the matrix product A128064 (unsigned) * A000045.
From R. J. Mathar, Jul 13 2009: (Start)
a(n) = A045925(n) + A045925(n-1).
a(n) = 2*a(n-1) + a(n-2) - 2*a(n-3) - a(n-4).
G.f.: x*(1+x)*(1+x^2)/(x^2+x-1)^2. (End)
a(n) = A238344(3n-2,n-1). - Alois P. Heinz, Apr 11 2014
From Vladimir Reshetnikov, Oct 28 2015: (Start)
a(n) = ((n+1)*F(n)+(n-1)*L(n))/2, where L(n) are Lucas numbers (A000032).
E.g.f.: (exp(phi*x)*(phi^3*x-1)-exp(-x/phi)*(phi^3+x)/phi)/(sqrt(5)*phi)+1, where phi=(1+sqrt(5))/2.
(End)

Extensions

More terms from Stefan Steinerberger, Dec 28 2007

A169630 a(n) = n times the square of Fibonacci(n).

Original entry on oeis.org

0, 1, 2, 12, 36, 125, 384, 1183, 3528, 10404, 30250, 87131, 248832, 705757, 1989806, 5581500, 15586704, 43356953, 120187008, 332134459, 915304500, 2516113236, 6900949462, 18888143927, 51599794176, 140718765625, 383142771674, 1041660829548, 2828107288188, 7668512468789
Offset: 0

Views

Author

R. J. Mathar, Mar 13 2010

Keywords

Crossrefs

Cf. A000045, A007598, A045925, A282464 (partial sums).

Programs

  • Haskell
    a169630 n = a007598 n * n  -- Reinhard Zumkeller, Sep 01 2013
    
  • Magma
    I:=[0,1,2,12,36,125]; [n le 6 select I[n] else 4*Self(n-1)-10*Self(n-3)+4*Self(n-5)-Self(n-6): n in [1..30]]; // Vincenzo Librandi, Dec 19 2012
    
  • Maple
    A169630 := proc(n) n*(combinat[fibonacci](n))^2 ; end proc:
  • Mathematica
    CoefficientList[Series[x*(1 - 2*x + 4*x^2 - 2*x^3 + x^4)/((1 + x)^2*(x^2 - 3*x + 1)^2), {x, 0, 40}], x] (* Vincenzo Librandi, Dec 19 2012 *)
    Table[n Fibonacci[n]^2,{n,0,30}] (* or *) LinearRecurrence[{4,0,-10,0,4,-1},{0,1,2,12,36,125},30] (* Harvey P. Dale, Jul 07 2017 *)
  • PARI
    vector(40, n, n--; n*fibonacci(n)^2) \\ Michel Marcus, Jul 09 2015

Formula

a(n) = A045925(n)*A000045(n) = n*A007598(n) = n *(A000045(n))^2.
a(n) = 4*a(n-1) -10*a(n-3) +4*a(n-5) -a(n-6).
G.f.: x*(1-2*x+4*x^2-2*x^3+x^4)/((1+x)^2*(x^2-3*x+1)^2).
a(n) = n*(((3 + sqrt(5))/2)^n + ((3 - sqrt(5))/2)^n - 2*(-1)^n)/5 (Bogdanowicz). - Stefano Spezia, May 05 2024

A190062 a(n) = n*Fibonacci(n) - Sum_{i=0..n-1} Fibonacci(i).

Original entry on oeis.org

0, 1, 1, 4, 8, 18, 36, 71, 135, 252, 462, 836, 1496, 2653, 4669, 8164, 14196, 24566, 42332, 72675, 124355, 212156, 360986, 612744, 1037808, 1754233, 2959801, 4985476, 8384480, 14080602, 23614932, 39556031, 66181311, 110608188, 184670694
Offset: 0

Views

Author

Bruno Berselli, May 04 2011

Keywords

Crossrefs

Programs

  • Magma
    [0] cat [n*Fibonacci(n)-(&+[Fibonacci(k): k in [0..n-1]]): n in [1..34]];
    
  • Mathematica
    CoefficientList[Series[x (1 - 2 x + 2 x^2) / ((1 - x) (1 - x - x^2)^2), {x, 0, 35}], x] (* Vincenzo Librandi, Aug 19 2013 *)
  • PARI
    concat(0, Vec(x*(1-2*x+2*x^2)/((1-x)*(1-x-x^2)^2) + O(x^50))) \\ Altug Alkan, Nov 13 2015

Formula

G.f.: x*(1-2*x+2*x^2)/((1-x)*(1-x-x^2)^2).
a(n) = A045925(n) - A000071(n+1).
a(n) = (n-1)*Fibonacci(n) - Fibonacci(n-1) + 1.
a(n) = (((2*n-1)*r-5)*(1+r)^n-((2*n-1)*r+5)*(1-r)^n)/(10*2^n)+1, where r=sqrt(5).

A131410 A127647 * A000012.

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 3, 3, 3, 3, 5, 5, 5, 5, 5, 8, 8, 8, 8, 8, 8, 13, 13, 13, 13, 13, 13, 13, 21, 21, 21, 21, 21, 21, 21, 21, 34, 34, 34, 34, 34, 34, 34, 34, 34, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 144, 144, 144
Offset: 1

Views

Author

Gary W. Adamson, Jul 08 2007

Keywords

Comments

Row sums = A045925, n*Fib(n): (1, 2, 6, 12, 25, 48,...).

Examples

			First few rows of the triangle are:
1;
1, 1;
2, 2, 2;
3, 3, 3, 3;
5, 5, 5, 5, 5;
8, 8, 8, 8, 8, 8;
...
		

Crossrefs

Programs

  • Haskell
    a131410 n k = a131410_tabl !! (n-1) !! (n-1)
    a131410_row n = a131410_tabl !! (n-1)
    a131410_tabl = zipWith replicate [1..] $ tail a000045_list
    -- Reinhard Zumkeller, Oct 07 2012
  • Mathematica
    Table[Fibonacci[n], {n, 15}, {n}] // Flatten (* Vincenzo Librandi, Jan 28 2017 *)

Formula

A127647 * A000012 as infinite lower triangular matrices.
Partial sums of A127647 starting from the right, read by rows.
By rows, F(n) occurs n times.

A146005 a(n) = n*Lucas(n).

Original entry on oeis.org

0, 1, 6, 12, 28, 55, 108, 203, 376, 684, 1230, 2189, 3864, 6773, 11802, 20460, 35312, 60707, 104004, 177631, 302540, 513996, 871266, 1473817, 2488368, 4194025, 7057518, 11858508, 19898116, 33345679, 55814940, 93320819, 155867104
Offset: 0

Views

Author

R. J. Mathar, Oct 26 2008

Keywords

Programs

  • Magma
    I:=[0, 1, 6, 12]; [n le 4 select I[n] else 2*Self(n-1) + Self(n-2) - 2*Self(n-3) - Self(n-4): n in [1..40]]; // Vincenzo Librandi, Dec 13 2012
  • Mathematica
    Table[LucasL[n, 1]*n, {n, 0, 36}] (* Zerinvary Lajos, Jul 09 2009 *)
    CoefficientList[Series[x * (1 + 4*x - x^2)/(1 - x - x^2)^2, {x, 0, 40}], x] (* Vincenzo Librandi, Dec 13 2012 *)
    LinearRecurrence[{2,1,-2,-1},{0,1,6,12},40] (* Harvey P. Dale, Apr 03 2013 *)

Formula

a(n) = n*A000032(n).
G.f.: x(1+4x-x^2)/(1-x-x^2)^2.
a(n) = 2*a(n-1)+a(n-2)-2*a(n-3)-a(n-4).
a(n) = A000045(n)-5*A000045(n+1)+5*A010049(n+1).
a(n) = A045925(n)+2*A099920(n-1).
E.g.f.: x*exp(x/2)*(cosh(sqrt(5)*x/2) + sqrt(5)*sinh(sqrt(5)*x/2)). - G. C. Greubel, Jan 30 2016

A086804 a(0)=0; for n > 0, a(n) = (n+1)^(n-2)*2^(n^2).

Original entry on oeis.org

0, 1, 16, 2048, 1638400, 7247757312, 164995463643136, 18446744073709551616, 9803356117276277820358656, 24178516392292583494123520000000, 271732164163901599116133024293512544256
Offset: 0

Views

Author

Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 05 2003

Keywords

Comments

Discriminant of Chebyshev polynomial U_n (x) of second kind.
Chebyshev second kind polynomials are defined by U(0)=0, U(1)=1 and U(n) = 2xU(n-1) - U(n-2) for n > 1.
The absolute value of the discriminant of Pell polynomials is a(n-1).
Pell polynomials are defined by P(0)=0, P(1)=1 and P(n) = 2x P(n-1) + P(n-2) if n > 1. - Rigoberto Florez, Sep 01 2018

References

  • Theodore J. Rivlin, Chebyshev polynomials: from approximation theory to algebra and number theory, 2. ed., Wiley, New York, 1990; p. 219, 5.1.2.

Crossrefs

Programs

  • Magma
    [0] cat [(n+1)^(n-2)*2^(n^2): n in [1..10]]; // G. C. Greubel, Nov 11 2018
  • Mathematica
    Join[{0},Table[(n+1)^(n-2) 2^n^2,{n,10}]] (* Harvey P. Dale, May 01 2015 *)
  • PARI
    a(n)=if(n<1,0,(n+1)^(n-2)*2^(n^2))
    
  • PARI
    a(n)=if(n<1,0,n++; poldisc(poltchebi(n)'/n))
    

Formula

a(n) = ((n+1)^(n-2))*2^(n^2), n >= 1, a(0):=0.
a(n) = ((2^(2*(n-1)))*Det(Vn(xn[1],...,xn[n])))^2, n >= 1, with the determinant of the Vandermonde matrix Vn with elements (Vn)i,j:= xn[i]^j, i=1..n, j=0..n-1 and xn[i]:=cos(Pi*i/(n+1)), i=1..n, are the zeros of the Chebyshev U(n,x) polynomials.
a(n) = ((-1)^(n*(n-1)/2))*(2^(n*(n-2)))*Product_{i=1..n}((d/dx)U(n,x)|_{x=xn[i]}), n >= 1, with the zeros xn[i], i=1..n, given above.

Extensions

Formula and more terms from Vladeta Jovovic, Aug 07 2003

A117202 Binomial transform of n*F(n).

Original entry on oeis.org

0, 1, 4, 15, 52, 170, 534, 1631, 4880, 14373, 41810, 120406, 343884, 975325, 2749852, 7713435, 21540304, 59917826, 166094370, 458998523, 1264919720, 3477182961, 9536877614, 26102772910, 71309161752, 194468551225, 529490287924
Offset: 0

Views

Author

Paul Barry, Mar 02 2006

Keywords

Comments

Binomial transform of A045925.
Number of acyclic subgraphs of the wheel graph W_n (on n+1 vertices) with exactly n-1 edges. - Emil R. Vaughan, Jun 12 2007
Equivalently, number of two-component spanning forests of the wheel graph W_n (on n+1 vertices). - Harry Richman, Jul 31 2023
Starting (1, 4, 15, 52, ...) = binomial transform of A136376. - Gary W. Adamson, Sep 03 2008

Crossrefs

Cf. A136376.
Cf. A004146 (number of spanning trees of wheel graph).

Programs

  • Mathematica
    Table[n Fibonacci[2n-1],{n,0,26}] (* or *) Table[Sum[Fibonacci[2k]*BernoulliB[2n-2k]*Binomial[2n,2k],{k,1,n}],{n,0,26}] (* or *) CoefficientList[Series[x(1-2x+2x^2)/(1-3x+x^2)^2 ,{x,0,26}],x] (* Indranil Ghosh, Feb 26 2017 *)
  • PARI
    a(n) = n*fibonacci(2*n-1); \\ Indranil Ghosh, Feb 26 2017
    
  • PARI
    concat(0, Vec(x*(1-2*x+2*x^2) / (1-3*x+x^2)^2 + O(x^30))) \\ Colin Barker, Feb 26 2017

Formula

G.f.: x*(1-2x+2x^2)/(1-3x+x^2)^2.
a(n) = 6*a(n-1)-11*a(n-2)+6*a(n-3)-a(n-4).
a(n) = Sum_{k=0..n} C(n,k)*k*F(k).
From Benoit Cloitre, Nov 29 2006: (Start)
a(n) = Sum_{k=1..n} F(2k)*B(2n-2k)*binomial(2n,2k) where F=Fibonacci numbers and B=Bernoulli numbers;
a(n) = n*F(2n-1). (End)
a(n) = (2^(-1-n)*(-(-5+sqrt(5))*(3+sqrt(5))^n + (3-sqrt(5))^n*(5+sqrt(5)))*n) / 5. - Colin Barker, Feb 26 2017
a(n) = (1/sqrt(5)) * n * (((1 + sqrt(5)) / 2)^(2*n-1) - ((1 - sqrt(5)) / 2)^(2*n-1)). - Harry Richman, Jul 31 2023
a(n) = round((1/sqrt(5)) * n * phi^(2n-1)), where phi = (1+sqrt(5))/2 is the golden ratio A001622. - Harry Richman, Jul 31 2023

A136391 a(n) = n*F(n) - (n-1)*F(n-1), where the F(j)'s are the Fibonacci numbers (F(0)=0, F(1)=1).

Original entry on oeis.org

1, 1, 4, 6, 13, 23, 43, 77, 138, 244, 429, 749, 1301, 2249, 3872, 6642, 11357, 19363, 32927, 55861, 94566, 159776, 269469, 453721, 762793, 1280593, 2147068, 3595422, 6013933, 10048559, 16773139, 27971549, 46605186, 77587084, 129063117, 214531397, 356346557
Offset: 1

Views

Author

Gary W. Adamson, Dec 28 2007

Keywords

Comments

By definition, the arithmetic mean of a(1) ... a(n) is equal to A000045(n).
Proof of the three-term recurrence formula: a(n+1) - a(n) - a(n-1) = ((n+1)*F(n+1) - n*F(n)) - (n*F(n) - (n-1)*F(n-1)) - ((n-1)*F(n-1) - (n-2)*F(n-2)) = (n+1)*F(n+1) - 2*n*F(n) + (n-2)*F(n-2) = (n+1)*(2*F(n) - F(n-2)) - 2*n*F(n) + (n-2)*F(n-2) = 2*F(n) - 3*F(n-2) = F(n-1) + F(n-3) = L(n-2). - Giuseppe Coppoletta, Sep 01 2014

Examples

			a(6) = 23 = 6*F(6) - 5*F(5) = 6*8 - 5*5 = 48 - 25.
		

Crossrefs

Programs

  • Julia
    # The function 'fibrec' is defined in A354044.
    function A136391(n)
        a, b = fibrec(n - 1)
        n*b - (n - 1)*a
    end
    println([A136391(n) for n in 1:35]) # Peter Luschny, May 18 2022
  • Maple
    with(combinat): seq(n*fibonacci(n)-(n-1)*fibonacci(n-1),n=1..30); # Emeric Deutsch, Jan 01 2008
  • Mathematica
    Table[n Fibonacci[n] - (n-1) Fibonacci[n-1], {n, 1, 20}] (* Vladimir Reshetnikov, Oct 28 2015 *)
  • PARI
    Vec(x*(1-x)*(1+x^2)/(1-x-x^2)^2 + O(x^100)) \\ Altug Alkan, Oct 28 2015
    

Formula

Equals A128064 * A000045.
From R. J. Mathar, Nov 25 2008: (Start)
a(n) = 2*a(n-1) + a(n-2) - 2*a(n-3) - a(n-4) = A045925(n) - A045925(n-1).
G.f.: x*(1 - x)*(1 + x^2)/(1 - x - x^2)^2.
a(n) = A014286(n-1) - A014286(n-2), n>3. (End)
Recurrence: a(n+1) = a(n) + a(n-1) + L(n-2) for n>1, where L = A000032 (see proof in Comments section). - Giuseppe Coppoletta, Sep 01 2014
E.g.f.: (exp(x*phi)/phi+exp(-x/phi)*phi)*(x+1)/sqrt(5)-1, where phi=(1+sqrt(5))/2. - Vladimir Reshetnikov, Oct 28 2015
a(n) = F(n-1) + n*F(n-2). - Bruno Berselli, Jul 26 2017

Extensions

More terms from Emeric Deutsch, Jan 01 2008
Previous Showing 11-20 of 28 results. Next