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 1-6 of 6 results.

A136158 Triangle whose rows are generated by A136157^n * [1, 1, 0, 0, 0, ...].

Original entry on oeis.org

1, 1, 1, 3, 4, 1, 9, 15, 7, 1, 27, 54, 36, 10, 1, 81, 189, 162, 66, 13, 1, 243, 648, 675, 360, 105, 16, 1, 729, 2187, 2673, 1755, 675, 153, 19, 1, 2187, 7290, 10206, 7938, 3780, 1134, 210, 22, 1, 6561, 24057, 37908, 34020, 19278, 7182, 1764, 276, 25, 1
Offset: 0

Views

Author

Gary W. Adamson, Dec 16 2007

Keywords

Comments

Triangle T(n,k), 0 <= k <= n, read by rows given by [1,2,0,0,0,0,0,0,0,0,...] DELTA [1,0,0,0,0,0,0,0,...] where DELTA is the operator defined in A084938. - Philippe Deléham, Dec 17 2007
Equals A080419 when first column is removed (here). - Georg Fischer, Jul 25 2023

Examples

			First few rows of the triangle:
    1;
    1,    1;
    3,    4,    1;
    9,   15,    7,    1;
   27,   54,   36,   10,   1;
   81,  189,  162,   66,  13,   1;
  243,  648,  675,  360, 105,  16,  1;
  729, 2187, 2673, 1755, 675, 153, 19, 1;
  ...
		

Crossrefs

Programs

  • Magma
    A136158:= func< n,k | n eq 0 select 1 else 3^(n-k-1)*(n+2*k)* Binomial(n, k)/n >;
    [A136158(n, k): k in [0..n], n in [0..12]]; // G. C. Greubel, Dec 22 2023; Dec 27 2023
    
  • Mathematica
    A136158[n_,k_]:= If[n==0, 1, 3^(n-k-1)*(n+2*k)*Binomial[n,k]/n];
    Table[A136158[n, k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Dec 22 2023; Dec 27 2023 *)
  • PARI
    T(n,k) = if ((n<0) || (k<0), return(0)); if ((n==0) && (k==0), return(1)); if (n==1, if (k<=1, return(1))); 3*T(n-1,k) + T(n-1,k-1);
    tabl(nn) = for (n=0, nn, for (k=0, n, print1(T(n, k), ", ")); print); \\ Michel Marcus, Jul 25 2023
    
  • SageMath
    def A136158(n,k): return 1 if (n==0) else 3^(n-k-1)*((n+2*k)/n)*binomial(n, k)
    flatten([[A136158(n, k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Dec 22 2023; Dec 27 2023

Formula

Sum_{k=0..n} T(n, k) = A081294(n).
Given A136157 = M, an infinite lower triangular bidiagonal matrix with (3, 3, 3, ...) in the main diagonal, (1, 1, 1, ...) in the subdiagonal and the rest zeros; rows of A136157 are generated from M^n * [1, 1, 0, 0, 0, ...], given a(0) = 1.
T(n, k) = A038763(n,n-k). - Philippe Deléham, Dec 17 2007
T(n, k) = 3*T(n-1, k) + T(n-1, k-1) for n > 1, T(0,0) = T(1,1) = T(1,0) = 1. - Philippe Deléham, Oct 30 2013
Sum_{k=0..n} T(n, k)*x^k = (1+x)*(3+x)^(n-1), n >= 1. - Philippe Deléham, Oct 30 2013
G.f.: (1-2*x)/(1-3*x-x*y). - R. J. Mathar, Aug 11 2015
From G. C. Greubel, Dec 22 2023: (Start)
T(n, 0) = A133494(n).
T(n, 1) = A006234(n+2).
T(n, 2) = A080420(n-2).
T(n, 3) = A080421(n-3).
T(n, 4) = A080422(n-4).
T(n, 5) = A080423(n-5).
T(n, n) = A000012(n).
T(n, n-1) = A016777(n-1).
T(n, n-2) = A062741(n-1).
Sum_{k=0..n} (-1)^k * T(n, k) = 0^n = A000007(n).
Sum_{k=0..floor(n/2)} T(n-k, k) = A003688(n).
Sum_{k=0..floor(n/2)} (-1)^k * T(n-k, k) = A001519(n). (End)
From G. C. Greubel, Dec 27 2023: (Start)
T(n, k) = 3^(n-k-1)*(n+2*k)*binomial(n,k)/n, for n > 0, with T(0, 0) = 1.
T(n, k) = (-1)^k * A164948(n, k). (End)

Extensions

More terms from Philippe Deléham, Dec 17 2007

A080420 a(n) = (n+1)*(n+6)*3^n/6.

Original entry on oeis.org

1, 7, 36, 162, 675, 2673, 10206, 37908, 137781, 492075, 1732104, 6022998, 20726199, 70681653, 239148450, 803538792, 2683245609, 8910671247, 29443957164, 96855122250, 317297380491, 1035574967097, 3368233731366, 10920608743932, 35303692060125, 113819103201843
Offset: 0

Views

Author

Paul Barry, Feb 19 2003

Keywords

Comments

a(n-1) is the number of words of length n defined on 5 letters that have exactly one a and no b's or exactly two b's and no a's. For example, for n=3, a(2) = 36 since the words are (number of permutations in parentheses): acc (3), add (3), aee (3), acd (6), ace (6), ade (6), bbc (3), bbd (3), bbe (3). - Enrique Navarrete, Jun 10 2025

Crossrefs

T(n,2) in triangle A080419.

Programs

  • Magma
    [(n+1)*(n+6)*3^n/6: n in [0..30]]; // Vincenzo Librandi, Aug 05 2013
    
  • Mathematica
    CoefficientList[Series[(1 - 2 x) / (1 - 3 x)^3, {x, 0, 30}], x] (* Vincenzo Librandi, Aug 05 2013 *)
    Table[(n+1)(n+6)3^n/6,{n,0,30}] (* or *) LinearRecurrence[{9,-27,27},{1,7,36},30] (* Harvey P. Dale, Apr 02 2019 *)
  • SageMath
    [(n+1)*(n+6)*3^n/6 for n in range(31)] # G. C. Greubel, Dec 22 2023

Formula

G.f.: (1-2*x)/(1-3*x)^3.
From G. C. Greubel, Dec 22 2023: (Start)
a(n) = (n+6)*A288834(n)/2, for n >= 1.
a(n) = A136158(n+2, 2).
E.g.f.: (1/2)*(2 + 8*x + 3*x^2)*exp(3*x). (End)
From Amiram Eldar, Jan 11 2024: (Start)
Sum_{n>=0} 1/a(n) = 17721/50 - 4356*log(3/2)/5.
Sum_{n>=0} (-1)^n/a(n) = 4392*log(4/3)/5 - 12591/50. (End)

A080421 a(n) = (n+1)*(n+2)*(n+9)*3^n/18.

Original entry on oeis.org

1, 10, 66, 360, 1755, 7938, 34020, 139968, 557685, 2165130, 8227494, 30705480, 112842639, 409209570, 1466777160, 5203870272, 18294856425, 63795240522, 220829678730, 759344158440, 2595329855811, 8821564534530, 29832927334956, 100419390748800, 336561864306525
Offset: 0

Views

Author

Paul Barry, Feb 19 2003

Keywords

Crossrefs

T(n,3) in triangle A080419.

Programs

  • Magma
    [(n+1)*(n+2)*(n+9)*3^n/18: n in [0..30]]; // Vincenzo Librandi, Aug 05 2013
    
  • Mathematica
    Table[((n+1)(n+2)(n+9)3^n)/18,{n,0,30}] (* or *) LinearRecurrence[ {12,-54,108,-81},{1,10,66,360},30] (* Harvey P. Dale, Mar 21 2012 *)
    CoefficientList[Series[(1 - 2 x) / (1 - 3 x)^4, {x, 0, 30}], x] (* Vincenzo Librandi, Aug 05 2013 *)
  • SageMath
    [(n+1)*(n+2)*(n+9)*3^(n-2)/2 for n in range(31)] # G. C. Greubel, Dec 22 2023

Formula

G.f.: (1-2*x)/(1-3*x)^4.
a(n) = A006503(n+1)*3^(n-1).
a(n) = 12*a(n-1)-54*a(n-2)+108*a(n-3)-81*a(n-4). - Harvey P. Dale, Mar 21 2012
From G. C. Greubel, Dec 22 2023: (Start)
a(n) = (n+9)*A036068(n-1).
a(n) = A136158(n+3, 3).
E.g.f.: (1/2)*(2 + 14*x + 15*x^2 + 3*x^3)*exp(3*x). (End)
From Amiram Eldar, Jan 11 2024: (Start)
Sum_{n>=0} 1/a(n) = 44172*log(3/2)/7 - 20050659/7840.
Sum_{n>=0} (-1)^n/a(n) = 44496*log(4/3)/7 - 14329629/7840. (End)

A080422 a(n) = (n+1)*(n+2)*(n+3)*(n+12)*3^n/72.

Original entry on oeis.org

1, 13, 105, 675, 3780, 19278, 91854, 415530, 1804275, 7577955, 30961359, 123589557, 483611310, 1860043500, 7046907660, 26344593252, 97328636181, 355781149065, 1288173125925, 4623863536215, 16466920464456, 58222325927898, 204499905118650, 713919106104750
Offset: 0

Views

Author

Paul Barry, Feb 19 2003

Keywords

Crossrefs

T(n, 4) in triangle A080419.
Cf. A136158.

Programs

  • Magma
    [(n+1)*(n+2)*(n+3)*(n+12)*3^n/72: n in [0..30]]; // Vincenzo Librandi, Aug 05 2013
    
  • Mathematica
    Table[(n + 1) (n + 2) (n + 3) (n + 12) 3^n/72, {n, 0, 30}] (* or *) LinearRecurrence[ {15, -90, 270, -405, 243}, {1, 13, 105, 675, 3780}, 30] (* Harvey P. Dale, Oct 22 2011 *)
    CoefficientList[Series[(1 - 2 x) / (1 - 3 x)^5, {x, 0, 30}], x] (* Vincenzo Librandi, Aug 05 2013 *)
  • SageMath
    [(n+1)*(n+2)*(n+3)*(n+12)*3^(n-3)/8 for n in range(31)] # G. C. Greubel, Dec 22 2023

Formula

G.f.: (1-2*x)/(1-3*x)^5.
For n>4, a(n)=15*a(n-1)-90*a(n-2)+270*a(n-3)-405*a(n-4)+243*a(n-5). - Harvey P. Dale, Oct 22 2011
From G. C. Greubel, Dec 22 2023: (Start)
a(n) = A136158(n+4,4).
E.g.f.: (1/8)*(8 + 80*x + 144*x^2 + 72*x^3 + 9*x^4)*exp(3*x). (End)
From Amiram Eldar, Jan 11 2024: (Start)
Sum_{n>=0} 1/a(n) = 662816499/42350 - 2122848*log(3/2)/55.
Sum_{n>=0} (-1)^n/a(n) = 2135808*log(4/3)/55 - 94614897/8470. (End)

A080423 a(n) = (n+1)*(n+2)*(n+3)*(n+4)*(n+15)*3^n/360.

Original entry on oeis.org

1, 16, 153, 1134, 7182, 40824, 214326, 1058508, 4979799, 22517352, 98513415, 419129802, 1741000716, 7083045648, 28296044604, 111232727064, 431026817373, 1648861601184, 6234757929477, 23328137324646, 86451332438394, 317576323243080, 1157228874847890, 4185605730648420
Offset: 0

Views

Author

Paul Barry, Feb 19 2003

Keywords

Crossrefs

T(n, 5) of triangle A080419.
Cf. A136158.

Programs

  • Magma
    [(n+1)*(n+2)*(n+3)*(n+4)*(n+15)*3^n/360: n in [0..30]]; // Vincenzo Librandi, Aug 05 2013
    
  • Mathematica
    CoefficientList[Series[(1 - 2 x) / (1 - 3 x)^6, {x, 0, 30}], x] (* Vincenzo Librandi, Aug 05 2013 *)
    Table[3^n*(n+15)*Binomial[n+4,4]/15, {n,0,30}] (* G. C. Greubel, Dec 22 2023 *)
  • SageMath
    [3^n*(n+15)*binomial(n+4,4)/15 for n in range(31)] # G. C. Greubel, Dec 22 2023

Formula

G.f.: (1-2*x)/(1-3*x)^6.
From G. C. Greubel, Dec 22 2023: (Start)
a(n) = A136158(n+5, 5).
E.g.f.: (1/40)*(40 + 520*x + 1320*x^2 + 1080*x^3 + 315*x^4 + 27*x^5)*exp(3*x). (End)
From Amiram Eldar, Jan 11 2024: (Start)
Sum_{n>=0} 1/a(n) = 215084880*log(3/2)/1001 - 99766344351/1145144.
Sum_{n>=0} (-1)^n/a(n) = 216218880*log(4/3)/1001 - 498108421095/8016008. (End)

A136159 A Chebyshev polynomial triangle of the first kind defined by T(n+1,x) = 3x*T(n,x) - T(n-1,x).

Original entry on oeis.org

1, 1, 3, -1, 9, -4, 27, -15, 1, 81, -54, 7, 243, -189, 36, -1, 729, -648, 162, -10, 2187, -2187, 675, -66, 1, 6561, -7290, 2673, -360, 13, 19683, -24057, 10206, -1755, 105, -1, 59049, -78732, 37908, -7938, 675, -16
Offset: 0

Views

Author

Gary W. Adamson, Dec 16 2007

Keywords

Comments

Row sums (unsigned) give A003688, (starting 1, 1, 4, 13, 43, 142, 469, ...).

Examples

			First few rows of the polynomials are:
1;
x;
3x^2 - 1;
9x^3 - 4x;
27x^4 - 15x^2 + 1;
81x^5 - 54x^3 + 7x;
243x^6 - 189x^4 + 36x^2 - 1;
729x^7 - 648x^5 + 162x^3 - 10x;
...
		

Crossrefs

Programs

  • PARI
    P(n) = if (n==0, 1, if (n==1, x, 3*x*P(n-1) - P(n-2)));
    row(n) = select(x->x!=0, Vec(P(n))); \\ Michel Marcus, Apr 15 2018

Formula

T(0,x) = 1, T(1,x) = x, T(n+1,x) = 3x*T(n,x) - T(n-1,x).
G.f: (l - tx)/(1 - 3tx + t^2).
Given triangle A136158, shift down columns to allow for (1, 1, 2, 2, 3, 3, ...) terms in each row.

Extensions

Corrected and extended by Philippe Deléham, Sep 12 2009
Keyword tabf set by Michel Marcus, Apr 15 2018
Showing 1-6 of 6 results.