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.

Previous Showing 11-20 of 21 results. Next

A096035 Triangle read by rows: T(n,k) = (n+1,k)-th element of (M^4-M)/3, where M is the infinite lower Pascal's triangle matrix, 1<=k<=n.

Original entry on oeis.org

1, 5, 2, 21, 15, 3, 85, 84, 30, 4, 341, 425, 210, 50, 5, 1365, 2046, 1275, 420, 75, 6, 5461, 9555, 7161, 2975, 735, 105, 7, 21845, 43688, 38220, 19096, 5950, 1176, 140, 8, 87381, 196605, 196596, 114660, 42966, 10710, 1764, 180, 9, 349525, 873810, 983025
Offset: 1

Views

Author

Gary W. Adamson, Jun 17 2004

Keywords

Examples

			Triangle begins:
1;
5,       2;
21,     15,    3;
85,     84,   30,   4;
341,   425,  210,  50,  5;
1365, 2046, 1275, 420, 75,  6;
		

Crossrefs

Cf. A007318. First column gives A002450. Row sums give A016127.

Programs

  • Maple
    P:= proc(n) option remember; local M; M:= Matrix(n, (i, j)-> binomial(i-1, j-1)); (M^4-M)/3 end: T:= (n, k)-> P(n+1)[n+1, k]: seq(seq(T(n, k), k=1..n), n=1..11);  # Alois P. Heinz, Oct 07 2009
  • Mathematica
    rows=11; M[n_] := M[n] = Array[Binomial, {n, n}, {0, 0}]; P[n_] := (MatrixPower[ M[n], 4] - M[n])/3; Table[P[rows+1][[n+1, 1 ;; n]], {n, 1, rows}] // Flatten (* Jean-François Alcover, Mar 11 2015 *)

Extensions

Edited and more terms from Alois P. Heinz, Oct 07 2009

A327317 Triangular array read by rows: row n shows the coefficients of this polynomial of degree n: p(x,n) = 2^(n-1) ((x+r)^n - (x+s)^n)/(r - s), where r = 2 and s = 1/2.

Original entry on oeis.org

1, 5, 4, 21, 30, 12, 85, 168, 120, 32, 341, 850, 840, 400, 80, 1365, 4092, 5100, 3360, 1200, 192, 5461, 19110, 28644, 23800, 11760, 3360, 448, 21845, 87376, 152880, 152768, 95200, 37632, 8960, 1024, 87381, 393210, 786384, 917280, 687456, 342720, 112896
Offset: 1

Views

Author

Clark Kimberling, Nov 03 2019

Keywords

Comments

p(x,n) is a strong divisibility sequence of polynomials. That is, gcd(p(x,h),p(x,k)) = p(x,gcd(h,k)). If x is an integer, then p(x,n) is a strong divisibility sequence of integers.

Examples

			First six rows:
     1;
     5,    4;
    21,   30,   12;
    85,  168,  120,   32;
   341,  850,  840,  400,   80;
  1365, 4092, 5100, 3360, 1200, 192;
The first six polynomials, not factored:
1, 5 + 4 x, 21 + 30 x + 12 x^2, 85 + 168 x + 120 x^2 + 32 x^3, 341 + 850 x + 840 x^2 + 400 x^3 + 80 x^4, 1365 + 4092 x + 5100 x^2 + 3360 x^3 + 1200 x^4 + 192 x^5.
The first six polynomials, factored:
1, 5 + 4 x, 3 (7 + 10 x + 4 x^2), (5 + 4 x) (17 + 20 x + 8 x^2), 341 + 850 x + 840 x^2 + 400 x^3 + 80 x^4, 3 (5 + 4 x) (7 + 10 x + 4 x^2) (13 + 10 x + 4 x^2).
		

Crossrefs

Cf. A327316, A002450 (x=0), A016137 (x=1), A001045 (x = -1), A016162 (x = 2), A016181 (x = 3), A016127 (x = -3), A016157 (x = 1/2).

Programs

  • Mathematica
    r = 2; s = 1/2; f[x_, n_] := 2^(n - 1) ((x + r)^n - (x + s)^n)/(r - s);
    Column[Table[Expand[f[x, n]], {n, 1, 5}]]
    c[x_, n_] := CoefficientList[Expand[f[x, n]], x]
    TableForm[Table[c[x, n], {n, 1, 10}]] (* A327317 array *)
    Flatten[Table[c[x, n], {n, 1, 12}]]   (* A327317 sequence *)

A385671 a(n) = Sum_{k=0..n} 2^k * 3^(n-k) * binomial(4*n+1,k) * binomial(4*n-k,n-k).

Original entry on oeis.org

1, 22, 774, 30458, 1260886, 53731512, 2333065354, 102643195068, 4559878830006, 204091261040552, 9189096061165784, 415734554486178378, 18884084064916032026, 860673634902720476392, 39339618388269633525564, 1802605962076744803396888, 82777622289467318635747446
Offset: 0

Views

Author

Seiichi Manyama, Aug 04 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n, 2^k*3^(n-k)*binomial(4*n+1, k)*binomial(4*n-k, n-k));

Formula

a(n) = [x^n] (1+2*x)^(4*n+1)/(1-3*x)^(3*n+1).
a(n) = [x^n] 1/((1-2*x) * (1-5*x)^(3*n+1)).
a(n) = Sum_{k=0..n} 5^k * (-3)^(n-k) * binomial(4*n+1,k).
a(n) = Sum_{k=0..n} 5^k * 2^(n-k) * binomial(3*n+k,k).

A016282 Expansion of 1/((1-2*x)*(1-4*x)*(1-5*x)).

Original entry on oeis.org

1, 11, 83, 535, 3171, 17871, 97483, 520055, 2731091, 14179231, 72992283, 373347975, 1900290211, 9635660591, 48715157483, 245723238295, 1237206060531, 6220389909951, 31239388241083, 156746696495015, 785932504682051, 3938458614335311, 19727477439571083
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[ Series[ 1/((1 - 2x)(1 - 4x)(1 - 5x)), {x, 0, 20} ], x ]
    LinearRecurrence[{11,-38,40},{1,11,83},30] (* Harvey P. Dale, Nov 29 2022 *)
  • PARI
    Vec(1/((1-2*x)*(1-4*x)*(1-5*x))+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012
  • Sage
    [(5^n - 2^n)/3-(4^n - 2^n)/2 for n in range(2,21)] # Zerinvary Lajos, Jun 05 2009
    

Formula

a(n) = (2/3)*2^n - 8*(4)^n + (25/3)*5^n. - Antonio Alberto Olivares, May 12 2012

A016295 Expansion of 1/((1-2x)(1-5x)(1-6x)).

Original entry on oeis.org

1, 13, 117, 905, 6461, 43953, 289717, 1868425, 11861421, 74423393, 462815717, 2858273145, 17556537181, 107373722833, 654414852117, 3977351721065, 24118423433741, 145982106270273, 882250466222917
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{13,-52,60},{1,13,117},20] (* Harvey P. Dale, Mar 26 2016 *)
  • Sage
    [(6^n - 2^n)/4-(5^n - 2^n)/3 for n in range(2,21)] # Zerinvary Lajos, Jun 05 2009

Formula

a(n) = A016129(n+1) - A016127(n+1). - Zerinvary Lajos, Jun 05 2009
a(n) = 13*a(n-1) - 52*a(n-2) + 60*a(n-3), n >= 3.
a(n) = 11*a(n-1) - 30*a(n-2) + 2^n, n >= 2. - Vincenzo Librandi, Mar 16 2011
a(n) = 7*a(n-1) - 10*a(n-2) + 6^n, n >= 2. - Vincenzo Librandi, Mar 16 2011
a(n) = 8*a(n-1) - 12*a(n-2) + 5^n, n >= 2. - Vincenzo Librandi, Mar 16 2011
a(n) = -5^(n+2)/3 + 9*6^n + 2^n/3. - R. J. Mathar, Mar 18 2011

A016633 Expansion of g.f. 1/((1-2*x)*(1-11*x)*(1-12*x)).

Original entry on oeis.org

1, 25, 447, 6989, 101759, 1417941, 19180519, 253983853, 3309800367, 42599540357, 542895780791, 6863463633117, 86197420501375, 1076563471968373, 13382900349107463, 165700329729679181, 2044564737700501583, 25152545442794015589, 308625999807796411735, 3778261997130507936445
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    [(648*12^n +2^(n+1)-5*11^(n+2))/45 : n in [0..20]]; // Vincenzo Librandi, Oct 09 2011
    
  • Mathematica
    CoefficientList[Series[1/((1 - 2 x) (1 - 11 x) (1 - 12 x)), {x, 0, 15}], x] (* Michael De Vlieger, Jan 31 2018 *)
  • PARI
    Vec(1/((1-2*x)*(1-11*x)*(1-12*x))+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012
  • Sage
    [(12^n - 2^n)/10-(11^n - 2^n)/9 for n in range(2,18)] # Zerinvary Lajos, Jun 05 2009
    

Formula

From Vincenzo Librandi, Oct 09 2011: (Start)
a(n) = (648*12^n + 2^(n+1) - 5*11^(n+2))/45.
a(n) = 23*a(n-1) - 132*a(n-2) + 2^n.
a(n) = 25*a(n-1) - 178*a(n-2) + 264*a(n-3), n >= 3. (End)
From Elmo R. Oliveira, Mar 26 2025: (Start)
E.g.f.: exp(2*x)*(648*exp(10*x) - 605*exp(9*x) + 2)/45.
a(n) = A016136(n+1) - A016135(n+1). (End)

A025992 Expansion of 1/((1-2*x)*(1-5*x)*(1-7*x)*(1-8*x)).

Original entry on oeis.org

1, 22, 313, 3666, 38493, 377286, 3529681, 31947322, 282198565, 2447183310, 20920905369, 176852694018, 1481626607917, 12322682753494, 101879323774177, 838170485025354, 6867569457133749, 56077266261254238
Offset: 0

Views

Author

Keywords

Comments

From Bruno Berselli, May 09 2013: (Start)
a(n) - 2*a(n-1), for n>0, gives A019928 (after 1);
a(n) - 5*a(n-1), for n>0, gives A016311 (after 1);
a(n) - 7*a(n-1), for n>0, gives A016297 (after 1);
a(n) - 8*a(n-1), for n>0, gives A016296 (after 1);
a(n) - 7*a(n-1) + 10*a(n-2), for n>1, gives A016177 (after 15);
a(n) - 9*a(n-1) + 14*a(n-2), for n>1, gives A016162 (after 13);
a(n) - 10*a(n-1) + 16*a(n-2), for n>1, gives A016161 (after 12);
a(n) - 12*a(n-1) + 35*a(n-2), for n>1, gives A016131 (after 10);
a(n) - 13*a(n-1) + 40*a(n-2), for n>1, gives A016130 (after 9);
a(n) - 15*a(n-1) + 56*a(n-2), for n>1, gives A016127 (after 7);
a(n) - 20*a(n-1) +131*a(n-2) -280*a(n-3), for n>2, gives A000079 (after 4);
a(n) - 17*a(n-1) +86*a(n-2) -112*a(n-3), for n>2, gives A000351 (after 25);
a(n) - 15*a(n-1) +66*a(n-2) -80*a(n-3), for n>2, gives A000420 (after 49);
a(n) - 14*a(n-1) +59*a(n-2) -70*a(n-3), for n>2, gives A001018 (after 64),
and naturally: a(n) - 22*a(n-1) + 171*a(n-2) - 542*a(n-3) + 560*a(n-4), for n>3, gives 0 (see Harvey P. Dale in Formula lines). (End)

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 30); Coefficients(R!(1/((1-2*x)*(1-5*x)*(1-7*x)*(1-8*x)))); // Bruno Berselli, May 09 2013
    
  • Mathematica
    CoefficientList[Series[1/((1-2x)(1-5x)(1-7x)(1-8x)),{x,0,30}],x] (* or *) LinearRecurrence[ {22,-171,542,-560},{1,22,313,3666},30] (* Harvey P. Dale, Jan 29 2013 *)
  • PARI
    a(n) = n+=3; (5*8^n-9*7^n+5*5^n-2^n)/90 \\ Charles R Greathouse IV, Oct 03 2016
    
  • Python
    def A025992(n): return (5*pow(8,n+3)-9*pow(7,n+3)+pow(5,n+4)-pow(2,n+3))//90
    print([A025992(n) for n in range(41)]) # G. C. Greubel, Dec 27 2024

Formula

a(0)=1, a(1)=22, a(2)=313, a(3)=3666, a(n) = 22*a(n-1) - 171*a(n-2) + 542*a(n-3) - 560*a(n-4). - Harvey P. Dale, Jan 29 2013
a(n) = (5*8^(n+3) - 9*7^(n+3) + 5^(n+4) - 2^(n+3))/90. - Yahia Kahloune, May 07 2013
E.g.f.: (1/90)*(-8*exp(2*x) + 625*exp(5*x) - 3087*exp(7*x) + 2560*exp(8*x)). - G. C. Greubel, Dec 27 2024

A016198 Expansion of g.f. 1/((1-x)*(1-2*x)*(1-5*x)).

Original entry on oeis.org

1, 8, 47, 250, 1281, 6468, 32467, 162590, 813461, 4068328, 20343687, 101722530, 508620841, 2543120588, 12715635707, 63578244070, 317891351421, 1589457019248, 7947285620527, 39736429151210, 198682147853201, 993410743460308, 4967053725690147, 24835268645227950
Offset: 0

Views

Author

N. J. A. Sloane, Dec 11 1999

Keywords

Crossrefs

Programs

Formula

a(n) = (25*5^n - 16*2^n + 3)/12. - Bruno Berselli, Feb 09 2011
a(n) = [(5^0-2^0) + (5^1-2^1) + ... + (5^n-2^n)]/3. - r22lou(AT)cox.net, Nov 14 2005
a(0)=1, a(n) = 5*a(n-1) + 2^(n+1) - 1. - Vincenzo Librandi, Feb 07 2011
From Elmo R. Oliveira, Mar 26 2025: (Start)
E.g.f.: exp(x)*(25*exp(4*x) - 16*exp(x) + 3)/12.
a(n) = 8*a(n-1) - 17*a(n-2) + 10*a(n-3).
a(n) = A016127(n+1) - A003463(n+2). (End)

Extensions

More terms from Wesley Ivan Hurt, May 05 2014

A093953 a(n) = rightmost term in M^n * [1,1,1], where M = a 3 X 3 matrix composed of the first 3 rows of A050166 (fill in the matrix with zeros): = [1 0 0 / 1 2 0 / 1 4 5].

Original entry on oeis.org

1, 10, 63, 344, 1781, 9030, 45403, 227524, 1138641, 5695250, 28480343, 142409904, 712065901, 3560362270, 17801876883, 89009515484
Offset: 0

Views

Author

Gary W. Adamson, Apr 18 2004

Keywords

Comments

A sequence relating to Catalan numbers.
a(n)/a(n-1) tends to 5, a Catalan number. E.g. a(6)/a(5) = 45403/9030 = 4.9948...
Generally, with M = an N X N matrix composed of rows of A050166 (along with zeros), M^n * [1,1,1...] generates terms [a, b, c, d...] such that sequences of which a,b,c,d...are members converge upon the Catalan numbers: 1, 2, 5, 14, 42, 132...
Companion (M^n)[3,2] = 4*A016127(n), (M^n)[3,3] = 5^n = A000351(n), so a(n) = a(n-1) + 4*A016127(n-1) + 5^(n-1) for n>0. - Lambert Klasen (lambert.klasen(AT)gmx.net), Jan 30 2005

Examples

			a(4) = 1781 since M^4 * [1,1,1] = [1, 31, 1781].
		

Crossrefs

Programs

  • PARI
    M=[1,0,0;1,2,0;1,4,5];for(i=0,16,print1((M^i)[3,1]", ")) \\ Klasen

Formula

Or simply with M=[1, 0, 0;1, 2, 0;1, 4, 5], a(n)=(M^n)[3, 1], (adds a leading 0 to sequence). - Lambert Klasen (lambert.klasen(AT)gmx.net), Jan 30 2005
G.f.: (1+2*x)/(1-8*x+17*x^2-10*x^3). - Colin Barker, Jan 31 2012

A102752 Array read by antidiagonals: T(n, k) = ((n+2)^k-(n-1)^k)/3.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 0, 1, 3, 3, 0, 1, 5, 9, 5, 0, 1, 7, 21, 27, 11, 0, 1, 9, 39, 85, 81, 21, 0, 1, 11, 63, 203, 341, 243, 43, 0, 1, 13, 93, 405, 1031, 1365, 729, 85, 0, 1, 15, 129, 715, 2511, 5187, 5461, 2187, 171, 0, 1, 17, 171, 1157, 5261, 15309, 25999, 21845, 6561, 341, 0, 1
Offset: 0

Views

Author

Lambert Klasen (lambert.klasen(AT)gmx.net) and Gary W. Adamson, Feb 09 2005

Keywords

Comments

Consider a 3 X 3 matrix M =
[n, 1, 1]
[1, n, 1]
[1, 1, n].
The n-th row of the array contains the values of the nondiagonal elements of M^k, k=0,1,.... (Corresponding diagonal entry = nondiagonal entry + (n-1)^k.)
Table:
n: row sequence G.f. cross references.
0: (2^n-(-1)^n)/3 1/((1+1x)(1-2x)) A001045 (Jacobsthal sequence)
1: (3^n-0^n)/3 1/(1-3x) A000244
2: (4^n-1^n)/3 1/((1-1x)(1-4x)) A002450
3: (5^n-2^n)/3 1/((1-2x)(1-5x)) A016127
4: (6^n-3^n)/3 1/((1-3x)(1-6x)) A016137
5: (7^n-4^n)/3 1/((1-4x)(1-7x)) A016150
6: (8^n-5^n)/3 1/((1-5x)(1-8x)) A016162
7: (9^n-6^n)/3 1/((1-6x)(1-9x)) A016172
8: (10^n-7^n)/3 1/((1-7x)(1-10x)) A016181
9: (11^n-8^n)/3 1/((1-8x)(1-11x)) A016187
10:(12^n-9^n)/3 1/((1-9x)(1-12x)) A016191
If r(n) denotes a row sequence, r(n+1)/r(n) converges to n+2.
Columns follow polynomials with certain binomial coefficients:
column: polynomial
0: 0
1: 1
2: 2*n + 1
3: 3*n^2+ 3*n + 3
4: 4*n^3+ 6*n^2+ 12*n + 5
5: 5*n^4+10*n^3+ 30*n^2+ 25*n + 11
6: 6*n^5+15*n^4+ 60*n^3+ 75*n^2+ 66*n + 21
7: 7*n^6+21*n^5+105*n^4+ 175*n^3+ 231*n^2+ 147*n + 43
8: 8*n^7+28*n^6+168*n^5+ 350*n^4+ 616*n^3+ 588*n^2+344*n+ 85
etc.
Coefficients are generated by the array T(n,k)=(2^(n-k-1)-(-1)^(n-k-1))/3*(binomial(k+(n-k-1),n-k-1)) read by antidiagonals.

Examples

			Array begins:
  0, 1, 1,  3,   5,   11, ...
  0, 1, 3,  9,  27,   81, ...
  0, 1, 5, 21,  85,  341, ...
  0, 1, 7, 39, 203, 1031, ...
  0, 1, 9, 63, 405, 2511, ...
  ...
		

Programs

  • PARI
    MM(n,N)=local(M);M=matrix(n,n);for(i=1,n, for(j=1,n,if(i==j,M[i,j]=N,M[i,j]=1)));M for(k=0,10, for(i=0,10,print1((MM(3,k)^i)[1,2],","));print())
Previous Showing 11-20 of 21 results. Next