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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A117715 Triangle, read by rows, T(n, k) = Fibonacci(n, k), where Fibonacci(n, x) is the Fibonacci polynomial.

Original entry on oeis.org

0, 1, 1, 0, 1, 2, 1, 2, 5, 10, 0, 3, 12, 33, 72, 1, 5, 29, 109, 305, 701, 0, 8, 70, 360, 1292, 3640, 8658, 1, 13, 169, 1189, 5473, 18901, 53353, 129949, 0, 21, 408, 3927, 23184, 98145, 328776, 927843, 2298912, 1, 34, 985, 12970, 98209, 509626, 2026009, 6624850, 18674305, 46866034
Offset: 0

Views

Author

Roger L. Bagula, Apr 13 2006

Keywords

Examples

			Triangle begins as:
  0;
  1,  1;
  0,  1,   2;
  1,  2,   5,   10;
  0,  3,  12,   33,   72;
  1,  5,  29,  109,  305,   701;
  0,  8,  70,  360, 1292,  3640,  8658;
  1, 13, 169, 1189, 5473, 18901, 53353, 129949;
		

References

  • Steven Wolfram, The Mathematica Book, Cambridge University Press, 3rd ed. 1996, page 728

Crossrefs

Cf. A000045, A117716, A049310, A073133, A157103 (antidiagonals).
Main diagonal and first lower diagonal give: A084844, A084845.
Cf. A352361.

Programs

  • Magma
    A117715:= func< n, k | k eq 0 select (n mod 2) else Evaluate(DicksonSecond(n-1, -1), k) >;
    [A117715(n, k): k in [0..n], n in [0..13]]; // G. C. Greubel, Oct 01 2024
    
  • Maple
    with(combinat):for n from 0 to 9 do seq(fibonacci(n,m), m = 0 .. n) od; # Zerinvary Lajos, Apr 09 2008
  • Mathematica
    Table[Fibonacci[n, k], {n,0,12}, {k,0,n}]//Flatten
  • Python
    from sympy import fibonacci
    def T(n, m): return 0 if n==0 else fibonacci(n, m)
    for n in range(21): print([T(n, m) for m in range(n + 1)]) # Indranil Ghosh, Aug 12 2017
    
  • SageMath
    def A117715(n,k): return lucas_number1(n, k, -1)
    flatten([[A117715(n,k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Oct 01 2024

Formula

T(n, 1) = A000045(n).
T(n, 3) = A006190(n).
T(n, 4) = A001076(n).
T(n, 5) = A052918(n-1).
T(5, k) = A057721(k).
T(6, k) = A124152(k).
T(n, k) = (-1)^(n-1)*A352361(n-k, n). - G. C. Greubel, Oct 01 2024

Extensions

Definition simplified by the Assoc. Editors of the OEIS, Nov 17 2009

A123747 Numerators of partial sums of a series for sqrt(5).

Original entry on oeis.org

1, 7, 41, 9, 239, 6227, 32059, 163727, 166301, 841229, 21215481, 106782837, 536618341, 538698461, 172897, 13538601629, 67813224223, 339532842359, 339895847771, 1700893049407, 42549895540939, 212857129279583, 1064706466190659, 1065035803419763, 5326468921246139
Offset: 0

Views

Author

Wolfdieter Lang, Nov 10 2006

Keywords

Comments

Denominators are given by A123748.
The sum over central binomial coefficients scaled by powers of 5, r(n) = Sum_{k=0..n} binomial(2*k,k)/5^k, has the limit lim_{n -> infinity} r(n) = sqrt(5). From the expansion of 1/sqrt(1-x) for x=4/5.

Examples

			a(3) = 9 because r(3) = 1+2/5+6/25+4/25 = 9/5 = a(3)/A123748(3).
		

Crossrefs

Cf. A001077/A001076 continued fraction convergents for sqrt(5).

Programs

  • GAP
    List([0..25], n-> NumeratorRat(Sum([0..n], k-> Binomial(2*k,k)/5^k )) ); # G. C. Greubel, Aug 10 2019
  • Magma
    [Numerator( (&+[Binomial(2*k,k)/5^k: k in [0..n]])): n in [0..25]]; // G. C. Greubel, Aug 10 2019
    
  • Maple
    A123747:=n-> numer(sum(binomial(2*k,k)/5^k, k=0..n)); seq(A123747(n), n=0..25); # G. C. Greubel, Aug 10 2019
  • Mathematica
    Table[Numerator[Sum[Binomial[2*k, k]/5^k, {k,0,n}]], {n, 0, 25}] (* G. C. Greubel, Aug 10 2019 *)
  • PARI
    vector(25, n, n--; numerator(sum(k=0,n, binomial(2*k,k)/5^k))) \\ G. C. Greubel, Aug 10 2019
    
  • Sage
    [numerator( sum(binomial(2*k,k)/5^k for k in (0..n)) ) for n in (0..25)] # G. C. Greubel, Aug 10 2019
    

Formula

a(n) = numerator(r(n)) with the rationals r(n) = Sum_{k=0..n} binomial(2*k,k)/5^k, in lowest terms.
r(n) = Sum_{k=0..n} ((2*k-1)!!/((2*k)!!))*(4/5)^k, n>=0, with the double factorials A001147 and A000165.

A270863 Self-composition of the Fibonacci sequence.

Original entry on oeis.org

0, 1, 2, 6, 17, 50, 147, 434, 1282, 3789, 11200, 33109, 97878, 289354, 855413, 2528850, 7476023, 22101326, 65338038, 193158521, 571033600, 1688143881, 4990651642, 14753839486, 43616704857, 128943855250, 381196100507, 1126928202714, 3331532438042, 9848993360069
Offset: 0

Views

Author

Oboifeng Dira, Mar 24 2016

Keywords

Comments

This sequence has the same relation to the Fibonacci numbers A000045 as A030267 has to the natural numbers A000027.
From Oboifeng Dira, Jun 28 2020: (Start)
This sequence can be generated from a family of composition pairs of generating functions g(f(x)), where k is an integer and where
f(x) = x/(1-k*x-x^2) and g(x) = (x+(k-1)*x^2)/(1-(3-2*k)*x-(3*k-k^2-1)*x^2).
Some cases of k values are:
k=-5, f(x) g.f. 0,A052918(-1)^n and g(x) g.f. 0,A081571
k=-4, f(x) g.f. A001076(-1)^(n+1) and g(x) g.f. 0,A081570
k=-3, f(x) g.f. A006190(-1)^(n+1) and g(x) g.f. 0,A081569
k=-2, f(x) g.f. A215936(n+2) and g(x) g.f. 0,A081568
k=-1, f(x) g.f. A039834(n+2) and g(x) g.f. 0,A081567
k=0, f(x) g.f. A000035 and g(x) g.f. 0,A001519(n+1)
k=1, f(x) g.f. A000045 and g(x) g.f. A000045
k=2, f(x) g.f. A000129 and g(x) g.f. 0,A039834(n+1)
k=3, f(x) g.f. A006190 and g(x) g.f. 0,A001519(-1)^n
k=4, f(x) g.f. A001076 and g(x) g.f. 0,A093129(-1)^n
k=5, f(x) g.f. 0,A052918 and g(x) g.f. 0,A192240(-1)^n
k=6, f(x) g.f. A005668 and g(x)=(x+5*x^2)/(1+9*x+19*x^2)
k=7, f(x) g.f. 0,A054413 and g(x)=(x+6*x^2)/(1+11*x+29*x^2).
(End)

Examples

			a(5) = 3*a(4)+a(3)-3*a(2)-a(1) = 51+6-6-1 = 50.
		

Crossrefs

Programs

  • Magma
    I:=[0, 1, 2, 6]; [m le 4 select I[m] else 3*Self(m-1)+Self(m-2)-3*Self(m-3)-Self(m-4): m in [1..30]]; // Marius A. Burtea, Aug 03 2019
  • Maple
    f:= x-> x/(1-x-x^2):
    a:= n-> coeff(series(f(f(x)), x, n+1), x, n):
    seq(a(n), n=0..30);
  • PARI
    a(n)=([0,1,0,0; 0,0,1,0; 0,0,0,1; -1,-3,1,3]^(n-1)*[1;2;6;17])[1,1] \\ Charles R Greathouse IV, Mar 24 2016
    
  • PARI
    concat(0, Vec(x*(1-x-x^2)/(1-3*x-x^2+3*x^3+x^4) + O(x^40))) \\ Colin Barker, Mar 24 2016
    

Formula

a(n) = 3*a(n-1)+a(n-2)-3*a(n-3)-a(n-4) for n > 3, a(0)=0, a(1)=1, a(2)=2, a(3)=6.
G.f.: x*(1-x-x^2) / (1-3*x-x^2+3*x^3+x^4). - Colin Barker, Mar 24 2016
G.f.: B(B(x)) where B(x) is the g.f. of A000045. - Joerg Arndt, Mar 25 2016
a(n) = (phi*((phi^2 + 5^(1/4)*sqrt(3*phi))^n - (phi^2 - 5^(1/4)*sqrt(3*phi))^n) + (psi^2 + 5^(1/4)*sqrt(3*psi))^n - (psi^2 - 5^(1/4)*sqrt(3*psi))^n)/(2^n * 5^(3/4) * sqrt(3*phi)), where phi = (sqrt(5) + 1)/2 is the golden ratio, and psi = 1/phi = (sqrt(5) - 1)/2. - Vladimir Reshetnikov, Aug 01 2019
0 = a(n)*(a(n) +6*a(n+1) -a(n+2)) +a(n+1)*(8*a(n+1) -9*a(n+2) +a(n+3)) +a(n+2)*(-8*a(n+2) +6*a(n+3)) +a(n+3)*(-a(n+3)) if n>=0. - Michael Somos, Feb 05 2022

A056565 Fibonomial coefficients.

Original entry on oeis.org

1, 21, 714, 19635, 582505, 16776144, 488605194, 14169550626, 411591708660, 11948265189630, 346934172869802, 10072785423545712, 292460526776698763, 8491396839675395415, 246543315138161480670, 7158243695757340957617, 207835653079349665473587
Offset: 0

Views

Author

Wolfdieter Lang, Jul 10 2000

Keywords

Crossrefs

Programs

  • Magma
    [ &*[Fibonacci(n+k): k in [0..6]]/3120: n in [1..16] ]; // Bruno Berselli, Apr 11 2011
    
  • Mathematica
    (Times@@@Partition[Fibonacci[Range[30]],7,1])/3120  (* Harvey P. Dale, Apr 10 2011 *)
  • PARI
    b(n, k)=prod(j=1, k, fibonacci(n+j)/fibonacci(j));
    vector(20, n, b(n-1, 7))  \\ Joerg Arndt, May 08 2016

Formula

a(n) = A010048(n+7, 7) =: Fibonomial(n+7, 7).
G.f.: 1/p(8, n) with p(8, n) = 1 - 21*x - 273*x^2 + 1092*x^3 + 1820*x^4 - 1092*x^5 - 273*x^6 + 21*x^7 + x^8 = (1 + x - x^2) * (1 - 4*x - x^2) * (1 + 11*x - x^2) * (1 - 29*x - x^2) (n=8 row polynomial of signed Fibonomial triangle A055870; see this entry for Knuth and Riordan references).
a(n) = 29*a(n-1) + a(n-2) + ((-1)^n) * A001657(n), n >= 2, a(0)=1, a(1)=21.
G.f.: exp( Sum_{k>=1} F(8*k)/F(k) * x^k/k ), where F(n) = A000045(n). - Seiichi Manyama, May 07 2025

Extensions

Offset corrected by Seiichi Manyama, May 07 2025

A091870 A trinomial transform of Fibonacci(3n).

Original entry on oeis.org

0, 1, 8, 53, 336, 2105, 13144, 81997, 511392, 3189169, 19888040, 124023461, 773419248, 4823095913, 30077155576, 187563189565, 1169656805184, 7294059356257, 45486249993032, 283655347025429, 1768894026280080
Offset: 0

Views

Author

Paul Barry, Feb 06 2004

Keywords

Comments

Binomial transform of A084326.
Second binomial transform of A001076(n) = Fibonacci(3n)/2.

Crossrefs

Cf. A084326.

Programs

  • GAP
    a:=[0,1];; for n in [3..30] do a[n]:=8*a[n-1]-11*a[n-2]; od; a; # G. C. Greubel, May 21 2019
  • Magma
    [n le 2 select n-1 else 8*Self(n-1) -11*Self(n-2): n in [1..30]]; // G. C. Greubel, May 21 2019
    
  • Mathematica
    LinearRecurrence[{8, -11}, {0, 1}, 30] (* G. C. Greubel, May 21 2019 *)
    CoefficientList[Series[x/(1 - 8 x + 11 x^2), {x, 0, 30}], x] (* Michael De Vlieger, Sep 22 2017 *)
  • PARI
    my(x='x+O('x^30)); concat([0], Vec(x/(1 -8*x +11*x^2))) \\ G. C. Greubel, May 21 2019
    
  • Sage
    [lucas_number1(n,8,11) for n in range(0, 30)] # Zerinvary Lajos, Apr 23 2009
    

Formula

G.f.: x/(1 - 8*x + 11*x^2).
a(n) = sqrt(5) * ((4+sqrt(5))^n - (4-sqrt(5))^n) / 10.
a(n) = Sum_{i=0..n} Sum_{j=0..n} (n!/(i!*j!*(n-i-j)!)) * Fibonacci(3*i) / 2.

A106707 a(n) = -A001353(n).

Original entry on oeis.org

0, -1, -4, -15, -56, -209, -780, -2911, -10864, -40545, -151316, -564719, -2107560, -7865521, -29354524, -109552575, -408855776, -1525870529, -5694626340, -21252634831, -79315912984, -296011017105, -1104728155436, -4122901604639, -15386878263120, -57424611447841
Offset: 0

Views

Author

Roger L. Bagula, May 30 2005

Keywords

Crossrefs

Programs

  • Magma
    I:=[0,-1]; [n le 2 select I[n] else 4*Self(n-1) - Self(n-2): n in [1..30]]; // G. C. Greubel, Feb 05 2018
  • Maple
    a[0]:=0: a[1]:=-1: for n from 2 to 27 do a[n]:=4*a[n-1]-a[n-2] od: seq(a[n],n=0..27);
  • Mathematica
    LinearRecurrence[{4,-1},{0,-1},30] (* Harvey P. Dale, Nov 01 2019 *)
  • PARI
    x='x+O('x^30); Vec(-x/(1-4*x+x^2)) \\ G. C. Greubel, Feb 05 2018
    

Formula

G.f.: -x/(1-4*x+x^2).
a(n) = 4*a(n-1) - a(n-2); a(0)=0, a(1)=-1.

Extensions

Edited by N. J. A. Sloane, Apr 30 2006
New name from Joerg Arndt, Sep 22 2023

A042937 Denominators of continued fraction convergents to sqrt(1000).

Original entry on oeis.org

1, 1, 2, 3, 5, 8, 53, 114, 281, 4329, 8939, 22207, 142181, 164388, 306569, 470957, 777526, 1248483, 78183472, 79431955, 157615427, 237047382, 394662809, 631710191, 4184923955, 9001558101, 22188040157, 341822160456, 705832361069, 1753486882594
Offset: 0

Views

Author

Keywords

Examples

			sqrt(1000) = 31.62... = 31 + 1/(1 + 1/(1 + ...)) with convergents 31/1, 32/1, 63/2, 95/3, 158/5, ... - _M. F. Hasler_, Nov 02 2019
		

Crossrefs

Cf. A042936 (numerators), A040968 (continued fraction), A010467 (decimals).
Analog for sqrt(m): A000129 (m=2), A002530 (m=3), A001076 (m=5), A041007 (m=6), A041009 (m=7), A041011 (m=8), A005663 (m=10), A041015 (m=11), A041017 (m=12), ..., A042933 (m=998), A042935 (m=999).

Programs

  • Mathematica
    Denominator[Convergents[Sqrt[1000], 30]] (* Vincenzo Librandi, Feb 01 2014 *)
  • PARI
    A42937=contfracpnqn(c=contfrac(sqrt(1000)),#c-1)[2,] \\ Possibly incorrect last term ignored. NB: a(n) = A42937[n+1]. For more terms use e.g. \p999, or compute any a(n) from this as in A042936. - M. F. Hasler, Nov 01 2019

Extensions

More terms from Vincenzo Librandi, Feb 01 2014

A048878 Generalized Pellian with second term of 9.

Original entry on oeis.org

1, 9, 37, 157, 665, 2817, 11933, 50549, 214129, 907065, 3842389, 16276621, 68948873, 292072113, 1237237325, 5241021413, 22201322977, 94046313321, 398386576261, 1687592618365, 7148757049721, 30282620817249, 128279240318717, 543399582092117, 2301877568687185
Offset: 0

Views

Author

Keywords

Examples

			a(n) = 4a(n-1) + a(n-2); a(0)=1, a(1)=9.
		

Crossrefs

Programs

  • Maple
    with(combinat): a:=n->5*fibonacci(n-1,4)+fibonacci(n,4): seq(a(n), n=1..16); # Zerinvary Lajos, Apr 04 2008
  • Mathematica
    LinearRecurrence[{4,1},{1,9},31] (* or *) CoefficientList[ Series[ (1+5x)/(1-4x-x^2),{x,0,30}],x] (* Harvey P. Dale, Jul 12 2011 *)
  • PARI
    { default(realprecision, 2000); for (n=0, 2000, a=round(((7+sqrt(5))*(2+sqrt(5))^n - (7-sqrt(5))*(2-sqrt(5))^n )/10*sqrt(5)); if (a > 10^(10^3 - 6), break); write("b048878.txt", n, " ", a); ); } \\ Harry J. Smith, May 31 2009

Formula

a(n) = ( (7+sqrt(5))(2+sqrt(5))^n - (7-sqrt(5))(2-sqrt(5))^n )/2*sqrt(5).
G.f.: (1+5*x)/(1-4*x-x^2). - Philippe Deléham, Nov 03 2008
a(n) = F(3*n+3) + F(3*n-2); F = A000045. - Yomna Bakr and Greg Dresden, May 25 2024

A094292 Number of (s(0), s(1), ..., s(n)) such that 0 < s(i) < 5 and |s(i) - s(i-1)| <= 1 for i = 1,2,...,n, s(0) = 2, s(n) = 4.

Original entry on oeis.org

0, 0, 1, 3, 9, 25, 68, 182, 483, 1275, 3355, 8811, 23112, 60580, 158717, 415715, 1088661, 2850645, 7463884, 19541994, 51163695, 133951675, 350695511, 918141623, 2403740304, 6293097000, 16475579353, 43133687427, 112925557953, 295643107825, 774003961940
Offset: 0

Views

Author

Herbert Kociemba, Jun 02 2004

Keywords

Comments

In general, a(n,m,j,k) = (2/m)*Sum_{r=1..m-1} sin(j*r*Pi/m)*sin(k*r*Pi/m)*(1+2*cos(Pi*r/m))^n is the number of (s(0), s(1), ..., s(n)) such that 0 < s(i) < m and |s(i) - s(i-1)| <= 1 for i = 1,2,...,n, s(0) = j, s(n) = k.
a(n+1) is an inverse Catalan transform of F(3n)/F(3). The g.f. may be obtained from that of A001076 under the mapping g(x)-> g(x(1-x)). - Paul Barry, Nov 17 2004
A transform of Fibonacci(2n): Fibonacci(2n) may be recovered as Sum_{k=0..2n} Sum_{j=0..k} binomial(0,2n-k)*binomial(k,j)(-1)^(k-j)*A094292(j). - Paul Barry, Jun 10 2005

Crossrefs

Programs

  • Mathematica
    Table[Sum[Fibonacci[n - 1 + i]/2, {i, 0, n - 1}], {n, 0, 27}]  (* Zerinvary Lajos, Jul 12 2009 *)
    Table[Fibonacci[n] (LucasL[n] - 1)/2, {n, 0, 20}] (* Vladimir Reshetnikov, Sep 27 2016 *)
  • MuPAD
    (numlib::fibonacci(2*n)-numlib::fibonacci(n))/2 $ n = 0..35; // Zerinvary Lajos, May 09 2008
    
  • PARI
    a(n) = (fibonacci(2*n) - fibonacci(n))/2; \\ Altug Alkan, Dec 17 2017

Formula

a(n) = (2/5)*Sum_{k=1..4} sin(2*Pi*k/5)*sin(4*Pi*k/5)*(1+2*cos(Pi*k/5))^n.
From Herbert Kociemba, Jun 16 2004: (Start)
a(n) = 4*a(n-1) - 3*a(n-2) - 2*a(n-3) + a(n-4).
G.f.: (x^2-x^3)/(1 - 4x + 3x^2 + 2x^3 - x^4). (End)
a(n) = (Fibonacci(2*n) - Fibonacci(n))/2. - Vladeta Jovovic, Jul 17 2004
a(n+1) = Sum_{k=0..floor(n/2)} binomial(n-k, k)*(-1)^k*F(3n-3k)/F(3). - Paul Barry, Nov 17 2004
a(n) = Sum_{k=0..floor(n/2)} binomial(n, 2k)*Fibonacci(2k). - Paul Barry, Jun 10 2005
a(n) = Sum_{k=0..n-1} Fibonacci(n+k-1)/2. - Gary Detlefs, Feb 22 2011
a(n) = Fibonacci(n)*(Lucas(n) - 1)/2. - Vladimir Reshetnikov, Sep 27 2016

Extensions

a(0) = a(1) = 0 added and offset changed to 0 by Vladimir Reshetnikov, Oct 04 2016

A110526 a(n+3) = 3*a(n+2) + 5*a(n+1) + a(n), a(0) = 0, a(1) = 1, a(2) = 3.

Original entry on oeis.org

0, 1, 3, 14, 58, 247, 1045, 4428, 18756, 79453, 336567, 1425722, 6039454, 25583539, 108373609, 459077976, 1944685512, 8237820025, 34895965611, 147821682470, 626182695490, 2652552464431, 11236392553213, 47598122677284
Offset: 0

Views

Author

Creighton Dement, Jul 24 2005

Keywords

Comments

A001076(n) = a(n) + a(n+1). Program "Superseeker" finds: A033887(n+1) = a(n+2) - a(n); Elements of even index in the sequence: A049661(n) = (F(6n+1)-1)/4; A015448(n+2) = a(n+2) + 2*a(n+1) + a(n)

Crossrefs

Programs

  • Maple
    seriestolist(series(-x/((1+x)*(x^2+4*x-1)), x=0,25)); -or- Floretion Algebra Multiplication Program, FAMP Code: 1jbaseseq[(- 'i + 'j - i' + j' - 'kk' - 'ik' - 'jk' - 'ki' - 'kj')(+ .5'i + .5i' + .5'jj' + .5'kk')]
  • Mathematica
    Table[(Fibonacci[3n+1]-(-1)^n)/4, {n, 0, 20}] (* Vladimir Reshetnikov, Oct 28 2015 *)
  • PARI
    concat(0, Vec(x/((1+x)*(1-x^2-4*x)) + O(x^100))) \\ Altug Alkan, Oct 28 2015

Formula

G.f.: -x/((1+x)*(x^2+4*x-1)).
a(n) = (-1)^n/2 * Sum_{k=0..n} (-1)^k*Fibonacci(3*k). - Gary Detlefs, Jan 03 2013
a(n) = (Fibonacci(3*n+1)-(-1)^n)/4, where Fibonacci(n) = A000045(n). - Vladimir Reshetnikov, Oct 28 2015
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