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 1-10 of 15 results. Next

A109466 Riordan array (1, x(1-x)).

Original entry on oeis.org

1, 0, 1, 0, -1, 1, 0, 0, -2, 1, 0, 0, 1, -3, 1, 0, 0, 0, 3, -4, 1, 0, 0, 0, -1, 6, -5, 1, 0, 0, 0, 0, -4, 10, -6, 1, 0, 0, 0, 0, 1, -10, 15, -7, 1, 0, 0, 0, 0, 0, 5, -20, 21, -8, 1, 0, 0, 0, 0, 0, -1, 15, -35, 28, -9, 1, 0, 0, 0, 0, 0, 0, -6, 35, -56, 36, -10, 1, 0, 0, 0, 0, 0, 0, 1, -21, 70, -84, 45, -11, 1, 0, 0, 0, 0
Offset: 0

Views

Author

Philippe Deléham, Aug 28 2005

Keywords

Comments

Inverse is Riordan array (1, xc(x)) (A106566).
Triangle T(n,k), 0 <= k <= n, read by rows, given by [0, -1, 1, 0, 0, 0, 0, 0, 0, ...] DELTA [1, 0, 0, 0, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938.
Modulo 2, this sequence gives A106344. - Philippe Deléham, Dec 18 2008
Coefficient array of the polynomials Chebyshev_U(n, sqrt(x)/2)*(sqrt(x))^n. - Paul Barry, Sep 28 2009

Examples

			Rows begin:
  1;
  0,  1;
  0, -1,  1;
  0,  0, -2,  1;
  0,  0,  1, -3,  1;
  0,  0,  0,  3, -4,   1;
  0,  0,  0, -1,  6,  -5,   1;
  0,  0,  0,  0, -4,  10,  -6,   1;
  0,  0,  0,  0,  1, -10,  15,  -7,  1;
  0,  0,  0,  0,  0,   5, -20,  21, -8,  1;
  0,  0,  0,  0,  0,  -1,  15, -35, 28, -9, 1;
From _Paul Barry_, Sep 28 2009: (Start)
Production array is
  0,    1,
  0,   -1,    1,
  0,   -1,   -1,   1,
  0,   -2,   -1,  -1,   1,
  0,   -5,   -2,  -1,  -1,  1,
  0,  -14,   -5,  -2,  -1, -1,  1,
  0,  -42,  -14,  -5,  -2, -1, -1,  1,
  0, -132,  -42, -14,  -5, -2, -1, -1,  1,
  0, -429, -132, -42, -14, -5, -2, -1, -1, 1 (End)
		

Crossrefs

Cf. A026729 (unsigned version), A000108, A030528, A124644.

Programs

  • Magma
    /* As triangle */ [[(-1)^(n-k)*Binomial(k, n-k): k in [0..n]]: n in [0.. 15]]; // Vincenzo Librandi, Jan 14 2016
  • Mathematica
    (* The function RiordanArray is defined in A256893. *)
    RiordanArray[1&, #(1-#)&, 13] // Flatten (* Jean-François Alcover, Jul 16 2019 *)

Formula

Number triangle T(n, k) = (-1)^(n-k)*binomial(k, n-k).
T(n, k)*2^(n-k) = A110509(n, k); T(n, k)*3^(n-k) = A110517(n, k).
Sum_{k=0..n} T(n,k)*A000108(k)=1. - Philippe Deléham, Jun 11 2007
From Philippe Deléham, Oct 30 2008: (Start)
Sum_{k=0..n} T(n,k)*A144706(k) = A082505(n+1).
Sum_{k=0..n} T(n,k)*A002450(k) = A100335(n).
Sum_{k=0..n} T(n,k)*A001906(k) = A100334(n).
Sum_{k=0..n} T(n,k)*A015565(k) = A099322(n).
Sum_{k=0..n} T(n,k)*A003462(k) = A106233(n). (End)
Sum_{k=0..n} T(n,k)*x^(n-k) = A053404(n), A015447(n), A015446(n), A015445(n), A015443(n), A015442(n), A015441(n), A015440(n), A006131(n), A006130(n), A001045(n+1), A000045(n+1), A000012(n), A010892(n), A107920(n+1), A106852(n), A106853(n), A106854(n), A145934(n), A145976(n), A145978(n), A146078(n), A146080(n), A146083(n), A146084(n) for x = -12,-11,-10,-9,-8,-7,-6,-5,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8,9,10,11,12 respectively. - Philippe Deléham, Oct 27 2008
Sum_{k=0..n} T(n,k)*x^k = A000007(n), A010892(n), A099087(n), A057083(n), A001787(n+1), A030191(n), A030192(n), A030240(n), A057084(n), A057085(n+1), A057086(n) for x = 0,1,2,3,4,5,6,7,8,9,10 respectively. - Philippe Deléham, Oct 28 2008
G.f.: 1/(1-y*x+y*x^2). - Philippe Deléham, Dec 15 2011
T(n,k) = T(n-1,k-1) - T(n-2,k-1), T(n,0) = 0^n. - Philippe Deléham, Feb 15 2012
Sum_{k=0..n} T(n,k)*x^(n-k) = F(n+1,-x) where F(n,x)is the n-th Fibonacci polynomial in x defined in A011973. - Philippe Deléham, Feb 22 2013
Sum_{k=0..n} T(n,k)^2 = A051286(n). - Philippe Deléham, Feb 26 2013
Sum_{k=0..n} T(n,k)*T(n+1,k) = -A110320(n). - Philippe Deléham, Feb 26 2013
For T(0,0) = 0, the signed triangle below has the o.g.f. G(x,t) = [t*x(1-x)]/[1-t*x(1-x)] = L[t*Cinv(x)] where L(x) = x/(1-x) and Cinv(x)=x(1-x) with the inverses Linv(x) = x/(1+x) and C(x)= [1-sqrt(1-4*x)]/2, an o.g.f. for the shifted Catalan numbers A000108, so the inverse o.g.f. is Ginv(x,t) = C[Linv(x)/t] = [1-sqrt[1-4*x/(t(1+x))]]/2 (cf. A124644 and A030528). - Tom Copeland, Jan 19 2016

A190958 a(n) = 2*a(n-1) - 10*a(n-2), with a(0) = 0, a(1) = 1.

Original entry on oeis.org

0, 1, 2, -6, -32, -4, 312, 664, -1792, -10224, -2528, 97184, 219648, -532544, -3261568, -1197696, 30220288, 72417536, -157367808, -1038910976, -504143872, 9380822016, 23803082752, -46202054656, -330434936832, -198849327104, 2906650714112, 7801794699264
Offset: 0

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Author

Keywords

Comments

For the difference equation a(n) = c*a(n-1) - d*a(n-2), with a(0) = 0, a(1) = 1, the solution is a(n) = d^((n-1)/2) * ChebyshevU(n-1, c/(2*sqrt(d))) and has the alternate form a(n) = ( ((c + sqrt(c^2 - 4*d))/2)^n - ((c - sqrt(c^2 - 4*d))/2)^n )/sqrt(c^2 - 4*d). In the case c^2 = 4*d then the solution is a(n) = n*d^((n-1)/2). The generating function is x/(1 - c*x + d^2) and the exponential generating function takes the form (2/sqrt(c^2 - 4*d))*exp(c*x/2)*sinh(sqrt(c^2 - 4*d)*x/2) for c^2 > 4*d, (2/sqrt(4*d - c^2))*exp(c*x/2)*sin(sqrt(4*d - c^2)*x/2) for 4*d > c^2, and x*exp(sqrt(d)*x) if c^2 = 4*d. - G. C. Greubel, Jun 10 2022

Crossrefs

Programs

  • Magma
    I:=[0,1]; [n le 2 select I[n] else 2*Self(n-1)-10*Self(n-2): n in [1..30]]; // Vincenzo Librandi, Sep 17 2011
    
  • Mathematica
    LinearRecurrence[{2,-10}, {0,1}, 50]
  • PARI
    a(n)=([0,1; -10,2]^n*[0;1])[1,1] \\ Charles R Greathouse IV, Apr 08 2016
    
  • SageMath
    [lucas_number1(n,2,10) for n in (0..50)] # G. C. Greubel, Jun 10 2022

Formula

G.f.: x / ( 1 - 2*x + 10*x^2 ). - R. J. Mathar, Jun 01 2011
E.g.f.: (1/3)*exp(x)*sin(3*x). - Franck Maminirina Ramaharo, Nov 13 2018
a(n) = 10^((n-1)/2) * ChebyshevU(n-1, 1/sqrt(10)). - G. C. Greubel, Jun 10 2022
a(n) = (1/3)*10^(n/2)*sin(n*arctan(3)) = Sum_{k=0..floor(n/2)} (-1)^k*3^(2*k)*binomial(n,2*k+1). - Gerry Martens, Oct 15 2022

A106854 Expansion of 1/(1-x*(1-5*x)).

Original entry on oeis.org

1, 1, -4, -9, 11, 56, 1, -279, -284, 1111, 2531, -3024, -15679, -559, 77836, 80631, -308549, -711704, 831041, 4389561, 234356, -21713449, -22885229, 85682016, 200108161, -228301919, -1228842724, -87333129, 6056880491, 6493546136, -23790856319, -56258586999, 62695694596, 343988629591
Offset: 0

Views

Author

Paul Barry, May 08 2005

Keywords

Comments

Row sums of Riordan array (1,x*(1-5*x)). In general, a(n) = Sum_{k=0..n}(-1)^(n-k)*binomial(k,n-k)*r^(n-k), yields the row sums of the Riordan array (1,x*(1-k*x)).

Crossrefs

Programs

  • Magma
    I:=[1,1]; [n le 2 select I[n] else Self(n-1) - 5*Self(n-2): n in [1..30]]; // G. C. Greubel, Jan 14 2018
  • Mathematica
    Join[{a=1,b=1},Table[c=b-5*a;a=b;b=c,{n,80}]] (* Vladimir Joseph Stephan Orlovsky, Jan 22 2011 *)
    CoefficientList[Series[1/(1-x(1-5x)),{x,0,40}],x] (* or *) LinearRecurrence[ {1,-5},{1,1},40] (* Harvey P. Dale, Jan 21 2012 *)
  • PARI
    Vec(1/(1-x+5*x^2) + O(x^99)) \\ Altug Alkan, Sep 06 2016
    
  • Sage
    [lucas_number1(n,1,5) for n in range(1,35)] # Zerinvary Lajos, Jul 16 2008
    

Formula

a(n) = ((1+sqrt(-19))^(n+1)-(1-sqrt(-19))^(n+1))/(2^(n+1)sqrt(-19)).
a(n) = Sum_{k=0..n} (-1)^(n-k)*binomial(k, n-k)*5^(n-k).
a(n) = 5^(n/2)(cos(-n*acot(sqrt(19)/19))-sqrt(19)sin(-n*acot(sqrt(19)/19))/19).
a(n) = a(n-1)-5*a(n-2), a(0)=1, a(1)=1. - Philippe Deléham, Oct 21 2008
a(n) = Sum_{k=0..n} A109466(n,k)*5^(n-k). - Philippe Deléham, Oct 25 2008
G.f.: Q(0)/2, where Q(k) = 1 + 1/( 1 - x*(2*k+1 -5*x)/( x*(2*k+2 -5*x) + 1/Q(k+1) )); (continued fraction). - Sergei N. Gladkovskii, Dec 07 2013

A145934 Expansion of 1/(1-x*(1-6*x)).

Original entry on oeis.org

1, 1, -5, -11, 19, 85, -29, -539, -365, 2869, 5059, -12155, -42509, 30421, 285475, 102949, -1609901, -2227595, 7431811, 20797381, -23793485, -148577771, -5816861, 885649765, 920550931, -4393347659, -9916653245, 16443432709
Offset: 0

Views

Author

Philippe Deléham, Oct 25 2008

Keywords

Comments

Row sums of Riordan array (1, x(1-6x)).
For positive n, a(n) equals the determinant of the n X n tridiagonal matrix with 1's along the main diagonal, 3's along the superdiagonal, and 2's along the subdiagonal (see Mathematica code below). - John M. Campbell, Jul 08 2011

Crossrefs

Programs

  • Magma
    I:=[1,1]; [n le 2 select I[n] else Self(n-1) - 6*Self(n-2): n in [1..30]]; // G. C. Greubel, Jan 14 2018
  • Mathematica
    Table[Det[Array[KroneckerDelta[#1, #2] + KroneckerDelta[#1, #2 + 1]*2 + KroneckerDelta[#1, #2 - 1]*3 &, {n, n}]], {n, 1, 40}] (* John M. Campbell, Jul 08 2011 *)
    LinearRecurrence[{1,-6}, {1,1}, 30] (* G. C. Greubel, Jan 14 2018 *)
  • PARI
    Vec(1/(1-x*(1-6*x))+O(x^99)) \\ Charles R Greathouse IV, Sep 23 2012
    
  • Sage
    [lucas_number1(n,1,6) for n in range(1, 29)] # Zerinvary Lajos, Apr 22 2009
    

Formula

a(n) = Sum_{k=0..n} A109466(n,k)*6^(n-k).
a(n) = a(n-1) - 6*a(n-2); a(0)=1, a(1)=1. - Philippe Deléham, Oct 25 2008

A145976 Expansion of 1/(1-x*(1-7*x)).

Original entry on oeis.org

1, 1, -6, -13, 29, 120, -83, -923, -342, 6119, 8513, -34320, -93911, 146329, 803706, -220597, -5846539, -4302360, 36623413, 66739933, -189623958, -656803489, 670564217, 5268188640, 574239121, -36303081359, -40322755206, 213798814307
Offset: 0

Views

Author

Philippe Deléham, Oct 26 2008

Keywords

Comments

Row sums of Riordan array (1,x(1-7x)).

Crossrefs

Programs

  • Magma
    I:=[1,1]; [n le 2 select I[n] else Self(n-1) - 7*Self(n-2): n in [1..30]]; // G. C. Greubel, Jan 19 2018
  • Mathematica
    Join[{a=1,b=1},Table[c=b-7*a;a=b;b=c,{n,80}]] (* Vladimir Joseph Stephan Orlovsky, Jan 22 2011 *)
    CoefficientList[Series[1/(1-x(1-7x)),{x,0,50}],x] (* or *) LinearRecurrence[{1,-7},{1,1},50] (* Harvey P. Dale, May 11 2011 *)
  • PARI
    Vec(1/(1-x*(1-7*x)) + O(x^40)) \\ Michel Marcus, Jan 29 2016
    
  • Sage
    [lucas_number1(n,1,7) for n in range(1, 29)] # Zerinvary Lajos, Apr 22 2009
    

Formula

a(n) = a(n-1) - 7*a(n-2), a(0)=1, a(1)=1.
a(n) = Sum_{k=0..n} A109466(n,k)*7^(n-k).

Extensions

Corrected by Zerinvary Lajos, Apr 22 2009
Corrected by D. S. McNeil, Aug 20 2010

A145978 Expansion of 1/(1-x*(1-8*x)).

Original entry on oeis.org

1, 1, -7, -15, 41, 161, -167, -1455, -119, 11521, 12473, -79695, -179479, 458081, 1893913, -1770735, -16922039, -2756159, 132620153, 154669425, -906291799, -2143647199, 5106687193, 22255864785, -18597632759, -196644551039, -47863488967, 1525292919345
Offset: 0

Views

Author

Philippe Deléham, Oct 26 2008

Keywords

Comments

Row sums of Riordan array (1,1(1-8x)).

Crossrefs

Programs

  • Magma
    I:=[1,1]; [n le 2 select I[n] else Self(n-1) - 8*Self(n-2): n in [1..30]]; // G. C. Greubel, Jan 19 2018
  • Mathematica
    LinearRecurrence[{1,-8},{1,1},50] (* G. C. Greubel, Jan 29 2016 *)
  • PARI
    Vec(1/(1-x*(1-8*x)) + O(x^40)) \\ Michel Marcus, Jan 29 2016
    
  • Sage
    [lucas_number1(n,1,8) for n in range(1, 27)] # Zerinvary Lajos, Apr 22 2009
    

Formula

a(n) = a(n-1) - 8*a(n-2), a(0)=1, a(1)=1.
a(n) = Sum_{k=0..n} A109466(n,k)*8^(n-k).

A146078 Expansion of 1/(1-x*(1-9*x)).

Original entry on oeis.org

1, 1, -8, -17, 55, 208, -287, -2159, 424, 19855, 16039, -162656, -307007, 1156897, 3919960, -6492113, -41771753, 16657264, 392603041, 242687665, -3290739704, -5474928689, 24141728647, 73416086848, -143859470975, -804604252607
Offset: 0

Views

Author

Philippe Deléham, Oct 27 2008

Keywords

Comments

Row sums of Riordan array (1, x(1-9x)).

Crossrefs

Programs

  • Magma
    I:=[1,1]; [n le 2 select I[n] else Self(n-1) - 9*Self(n-2): n in [1..30]]; // G. C. Greubel, Jan 19 2018
  • Mathematica
    LinearRecurrence[{1, -9}, {1, 1}, 100] (* G. C. Greubel, Jan 30 2016 *)
  • PARI
    x='x+O('x^30); Vec(1/(1-x+9*x^2)) \\ G. C. Greubel, Jan 19 2018
    
  • Sage
    [lucas_number1(n,1,9) for n in range(1, 27)] # Zerinvary Lajos, Apr 22 2009
    

Formula

a(n) = a(n-1) - 9*a(n-2), a(0)=1, a(1)=1.
a(n) = Sum_{k=0..n} A109466(n,k)*9^(n-k).
From G. C. Greubel, Jan 31 2016: (Start)
G.f.: 1/(1-x+9*x^2).
E.g.f.: exp(x/2)*(cos(sqrt(35)*x/2) + (1/sqrt(35))*sin(sqrt(35)*x/2)). (End)
a(n) = Product_{k=1..n} (1 + 6*cos(k*Pi/(n+1))). - Peter Luschny, Nov 28 2019
a(n) = 3^n * U(n, 1/6), where U(n, x) is the Chebyshev polynomial of the second kind. - Federico Provvedi, Mar 28 2022

A146083 Expansion of 1/(1 - x*(1 - 11*x)).

Original entry on oeis.org

1, 1, -10, -21, 89, 320, -659, -4179, 3070, 49039, 15269, -524160, -692119, 5073641, 12686950, -43123101, -182679551, 291674560, 2301149621, -907270539, -26219916370, -16239940441, 272179139629, 450818484480, -2543152051439
Offset: 0

Views

Author

Philippe Deléham, Oct 27 2008

Keywords

Comments

Row sums of Riordan array (1,x(1-11x)).

Crossrefs

Programs

Formula

a(n) = a(n-1)-11*a(n-2) ; a(0)=1, a(1)=1.
a(n) = Sum_{k=0..n} A109466(n,k)*11^(n-k).
From G. C. Greubel, Jan 31 2016: (Start)
G.f.: 1/(1-x+11*x^2).
E.g.f.: exp(x/2)*(cos(sqrt(43)*x/2) + (1/sqrt(43))*sin(sqrt(43)*x/2)).
(End)

A115155 Expansion of (eta(q^3) * eta(q^5))^3 + (eta(q) * eta(q^15))^3 in powers of q.

Original entry on oeis.org

1, 1, -3, -3, 5, -3, 0, -7, 9, 5, 0, 9, 0, 0, -15, 5, -14, 9, -22, -15, 0, 0, 34, 21, 25, 0, -27, 0, 0, -15, 2, 33, 0, -14, 0, -27, 0, -22, 0, -35, 0, 0, 0, 0, 45, 34, -14, -15, 49, 25, 42, 0, -86, -27, 0, 0, 66, 0, 0, 45, -118, 2, 0, 13, 0, 0, 0, 42, -102, 0, 0
Offset: 1

Views

Author

Michael Somos, Jan 14 2006

Keywords

Comments

The terms of A136549 differ only in sign from this sequence. - Michael Somos, Jun 14 2023

Examples

			G.f. = q + q^2 - 3*q^3 - 3*q^4 + 5*q^5 - 3*q^6 - 7*q^8 + 9*q^9 + 5*q^10 +...
		

Crossrefs

Programs

  • Magma
    A := Basis( CuspForms( Gamma1(15), 3), 80); A[1] + A[2] - 3*A[3] - 3*A[4] + 5*A[5] - 3*A[6] - 7*A[8]; /* Michael Somos, Oct 13 2015 */
  • Mathematica
    a[ n_] := SeriesCoefficient[ q (QPochhammer[ q^3] QPochhammer[ q^5])^3 + q^2 (QPochhammer[ q] QPochhammer[ q^15])^3, {q, 0, n}]; (* Michael Somos, May 24 2013 *)
  • PARI
    {a(n) = my(A); if( n<1, 0, n--; A = x * O(x^n); polcoeff( (eta(x^3 + A) * eta(x^5 + A))^3 + x * (eta(x + A) * eta(x^15 + A))^3, n))};
    
  • Sage
    A = CuspForms( Gamma1(15), 3, prec=80) . basis(); A[0] + A[1] - 3*A[2] - 3*A[3] + 5*A[4] - 3*A[5] - 7*A[7]; # Michael Somos, May 28 2013
    

Formula

a(n) is multiplicative with a(3^e) = (-3)^e, a(5^e) = 5^e, a(p^e) = p^e if e even else 0 if p == 7, 11, 13, 14 (mod 15), a(p^e) = a(p) * a(p^(e-1)) - p^2 * a(p^(e-2)) if p == 1, 2, 4, 8 (mod 15).
G.f. is a period 1 Fourier series which satisfies f(-1 / (15 t)) = 15^(3/2) (t/i)^3 f(t) where q = exp(2 Pi i t). - Michael Somos, Jun 23 2012
a(2^n) = A106853(n).
a(n) = A030220(n) + A136599(n). - Michael Somos, Oct 13 2015

A146084 Expansion of 1/(1-x(1-12x)).

Original entry on oeis.org

1, 1, -11, -23, 109, 385, -923, -5543, 5533, 72049, 5653, -858935, -926771, 9380449, 20501701, -92063687, -338084099, 766680145, 4823689333, -4376472407, -62260744403, -9743075519, 737385857317, 854302763545, -7994327524259
Offset: 0

Views

Author

Philippe Deléham, Oct 27 2008

Keywords

Comments

Row sums of Riordan array (1,x(1-12x)).

Crossrefs

Programs

Formula

a(n) = a(n-1)-12*a(n-2), a(0)=1, a(1)=1.
a(n) = Sum_{k, 0<=k<=n} A109466(n,k)*12^(n-k).
Showing 1-10 of 15 results. Next