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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A169793 Expansion of ((1-x)/(1-2*x))^6.

Original entry on oeis.org

1, 6, 27, 104, 363, 1182, 3653, 10836, 31092, 86784, 236640, 632448, 1661056, 4296192, 10961664, 27630592, 68889600, 170065920, 416071680, 1009582080, 2431254528, 5814222848, 13815054336, 32629850112, 76640681984, 179080003584, 416412598272, 963876225024
Offset: 0

Views

Author

N. J. A. Sloane, May 15 2010

Keywords

Comments

a(n) is the number of weak compositions of n with exactly 5 parts equal to 0. - Milan Janjic, Jun 27 2010
Except for an initial 1, this is the p-INVERT of (1,1,1,1,1,...) for p(S) = (1 - S)^6; see A291000. - Clark Kimberling, Aug 24 2017

Crossrefs

Cf. for ((1-x)/(1-2x))^k: A011782, A045623, A058396, A062109, A169792-A169797; a row of A160232.

Programs

  • Magma
    m:=30; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(((1-x)/(1-2*x))^6)); // G. C. Greubel, Oct 16 2018
    
  • Maple
    seq(coeff(series(((1-x)/(1-2*x))^6,x,n+1), x, n), n = 0 .. 30); # Muniru A Asiru, Oct 16 2018
  • Mathematica
    CoefficientList[Series[((1 - x)/(1 - 2 x))^6, {x, 0, 27}], x] (* Michael De Vlieger, Oct 15 2018 *)
  • PARI
    x='x+O('x^30); Vec(((1-x)/(1-2*x))^6) \\ G. C. Greubel, Oct 16 2018

Formula

G.f.: ((1-x)/(1-2*x))^6.
For n > 0, a(n) = 2^(n-9)*(n+7)*(n^4 + 38*n^3 + 419*n^2 + 1342*n + 1080)/15. - Bruno Berselli, Aug 07 2011

A176027 Binomial transform of A005563.

Original entry on oeis.org

0, 3, 14, 48, 144, 400, 1056, 2688, 6656, 16128, 38400, 90112, 208896, 479232, 1089536, 2457600, 5505024, 12255232, 27131904, 59768832, 131072000, 286261248, 622854144, 1350565888, 2919235584, 6291456000, 13522436096
Offset: 0

Views

Author

Paul Curtz, Dec 06 2010

Keywords

Comments

The numbers appear on the diagonal of a table T(n,k), where the left column contains the elements of A005563, and further columns are recursively T(n,k) = T(n,k-1)+T(n-1,k-1):
....0....-1.....0.....0.....0.....0.....0.....0.....0.....0.
....3.....3.....2.....2.....2.....2.....2.....2.....2.....2.
....8....11....14....16....18....20....22....24....26....28.
...15....23....34....48....64....82...102...124...148...174.
...24....39....62....96...144...208...290...392...516...664.
...35....59....98...160...256...400...608...898..1290..1806.
...48....83...142...240...400...656..1056..1664..2562..3852.
...63...111...194...336...576...976..1632..2688..4352..6914.
...80...143...254...448...784..1360..2336..3968..6656.11008.
...99...179...322...576..1024..1808..3168..5504..9472.16128.
..120...219...398...720..1296..2320..4128..7296.12800.22272.
The second column is A142463, the third A060626, the fourth essentially A035008 and the fifth essentially A016802. Transposing the array gives A005563 and its higher order differences in the individual rows.

Crossrefs

Programs

Formula

G.f.: x*(-3+4*x)/(2*x-1)^3. - R. J. Mathar, Dec 11 2010
a(n) = 2^(n-2)*n*(5+n). - R. J. Mathar, Dec 11 2010
a(n) = A127276(n) - A127276(n+1).
a(n+1)-a(n) = A084266(n+1).
a(n+2) = 16*A058396(n) for n > 0.
a(n) = 2*a(n-1) + A001792(n).
a(n) = A001793(n) - 2^(n-1) for n > 0. - Brad Clardy, Mar 02 2012
a(n) = Sum_{k=0..n-1} Sum_{i=0..n-1} (k+3) * C(n-1,i). - Wesley Ivan Hurt, Sep 20 2017
From Amiram Eldar, Aug 13 2022: (Start)
Sum_{n>=1} 1/a(n) = 1322/75 - 124*log(2)/5.
Sum_{n>=1} (-1)^(n+1)/a(n) = 132*log(3/2)/5 - 782/75. (End)

A058395 Square array read by antidiagonals. Based on triangular numbers (A000217) with each term being the sum of 2 consecutive terms in the previous row.

Original entry on oeis.org

1, 0, 1, 3, 1, 1, 0, 3, 2, 1, 6, 3, 4, 3, 1, 0, 6, 6, 6, 4, 1, 10, 6, 9, 10, 9, 5, 1, 0, 10, 12, 15, 16, 13, 6, 1, 15, 10, 16, 21, 25, 25, 18, 7, 1, 0, 15, 20, 28, 36, 41, 38, 24, 8, 1, 21, 15, 25, 36, 49, 61, 66, 56, 31, 9, 1, 0, 21, 30, 45, 64, 85, 102, 104, 80, 39, 10, 1, 28, 21, 36, 55, 81, 113, 146, 168, 160, 111, 48, 11, 1
Offset: 0

Views

Author

Henry Bottomley, Nov 24 2000

Keywords

Comments

Changing the formula by replacing T(2n, 0) = T(n, 3) with T(2n, 0) = T(n, m) for some other value of m would change the generating function to the coefficient of x^n in expansion of (1 + x)^k / (1 - x^2)^m. This would produce A058393, A058394, A057884 (and effectively A007318).

Examples

			The array T(n, k) starts:
[0] 1, 0,  3,   0,   6,   0,  10,    0,   15,    0, ...
[1] 1, 1,  3,   3,   6,   6,  10,   10,   15,   15, ...
[2] 1, 2,  4,   6,   9,  12,  16,   20,   25,   30, ...
[3] 1, 3,  6,  10,  15,  21,  28,   36,   45,   55, ...
[4] 1, 4,  9,  16,  25,  36,  49,   64,   81,  100, ...
[5] 1, 5, 13,  25,  41,  61,  85,  113,  145,  181, ...
[6] 1, 6, 18,  38,  66, 102, 146,  198,  258,  326, ...
[7] 1, 7, 24,  56, 104, 168, 248,  344,  456,  584, ...
[8] 1, 8, 31,  80, 160, 272, 416,  592,  800, 1040, ...
[9] 1, 9, 39, 111, 240, 432, 688, 1008, 1392, 1840, ...
		

Crossrefs

Rows are A000217 with zeros, A008805, A002620, A000217, A000290, A001844, A005899.
Columns are A000012, A001477, A016028.
The triangle A055252 also appears in half of the array.

Programs

  • Maple
    gf := n -> (1 + x)^n / (1 - x^2)^3: ser := n -> series(gf(n), x, 20):
    seq(lprint([n], seq(coeff(ser(n), x, k), k = 0..9)), n = 0..9); # Peter Luschny, Apr 12 2023
  • Mathematica
    T[0, k_] := If[OddQ[k], 0, (k+2)(k+4)/8];
    T[n_, k_] := T[n, k] = If[k == 0, 1, T[n-1, k-1] + T[n-1, k]];
    Table[T[n-k, k], {n, 0, 12}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Apr 13 2023 *)

Formula

T(n, k) = T(n-1, k-1) + T(n, k-1) with T(0, k) = 1, T(2*n, 0) = T(n, 3) and T(2*n + 1, 0) = 0. Coefficient of x^n in expansion of (1 + x)^k / (1 - x^2)^3.

A169794 Expansion of ((1-x)/(1-2*x))^7.

Original entry on oeis.org

1, 7, 35, 147, 553, 1925, 6321, 19825, 59906, 175504, 500864, 1397536, 3823680, 10282496, 27230464, 71129856, 183518720, 468213760, 1182433280, 2958376960, 7338426368, 18059821056, 44120473600, 107055742976, 258122317824, 618683957248, 1474700509184
Offset: 0

Views

Author

N. J. A. Sloane, May 15 2010

Keywords

Comments

a(n) is the number of weak compositions of n with exactly 6 parts equal to 0. - Milan Janjic, Jun 27 2010

Crossrefs

Cf. for ((1-x)/(1-2x))^k: A011782, A045623, A058396, A062109, A169792-A169797; a row of A160232.

Programs

  • Magma
    m:=30; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(((1-x)/(1-2*x))^7)); // G. C. Greubel, Oct 16 2018
  • Maple
    seq(coeff(series(((1-x)/(1-2*x))^7,x,n+1), x, n), n = 0 .. 30); # Muniru A Asiru, Oct 16 2018
  • Mathematica
    CoefficientList[Series[((1 - x)/(1 - 2 x))^7, {x, 0, 26}], x] (* Michael De Vlieger, Oct 15 2018 *)
  • PARI
    x='x+O('x^30); Vec(((1-x)/(1-2*x))^7) \\ G. C. Greubel, Oct 16 2018
    

Formula

G.f.: ((1-x)/(1-2*x))^7.
For n > 0, a(n) = 2^(n-11)*(n+3)*(n+6)*(n^4 + 54*n^3 + 931*n^2 + 5454*n + 5080)/45. - Bruno Berselli, Aug 07 2011

A169795 Expansion of ((1-x)/(1-2x))^8.

Original entry on oeis.org

1, 8, 44, 200, 806, 2984, 10364, 34232, 108545, 332688, 990736, 2878144, 8182432, 22823680, 62595328, 169090048, 450568960, 1185832960, 3085885440, 7947714560, 20275478528, 51272351744, 128605356032, 320145981440, 791358537728, 1943278714880, 4742573981696
Offset: 0

Views

Author

N. J. A. Sloane, May 15 2010

Keywords

Comments

a(n) is the number of weak compositions of n with exactly 7 parts equal to 0. - Milan Janjic, Jun 27 2010

Crossrefs

Cf. for ((1-x)/(1-2x))^k: A011782, A045623, A058396, A062109, A169792-A169797; a row of A160232.

Programs

  • Mathematica
    CoefficientList[Series[((1-x)/(1-2x))^8,{x,0,30}],x] (* Harvey P. Dale, Nov 24 2016 *)

Formula

G.f.: ((1-x)/(1-2*x))^8.
For n > 0, a(n) = 2^(n-12)*(n+9) * (n^6 + 75*n^5 + 1999*n^4 + 23169*n^3 + 115768*n^2 + 232284*n + 142800)/315. - Bruno Berselli, Aug 07 2011

A169796 Expansion of ((1-x)/(1-2x))^9.

Original entry on oeis.org

1, 9, 54, 264, 1134, 4446, 16272, 56412, 187137, 598417, 1854882, 5597172, 16498632, 47638512, 135048672, 376592064, 1034663040, 2804590080, 7509232640, 19880294400, 52088352768, 135173578752, 347680161792, 886900948992, 2245014454272, 5641949085696
Offset: 0

Views

Author

N. J. A. Sloane, May 15 2010

Keywords

Comments

a(n) is the number of weak compositions of n with exactly 8 parts equal to 0. - Milan Janjic, Jun 27 2010

Crossrefs

Cf. for ((1-x)/(1-2x))^k: A011782, A045623, A058396, A062109, A169792-A169797; a row of A160232.

Programs

  • Mathematica
    CoefficientList[Series[((1 - x)/(1 - 2 x))^9, {x, 0, 25}], x] (* Michael De Vlieger, Oct 15 2018 *)

Formula

G.f.: ((1-x)/(1-2*x))^9.
For n > 0, a(n) = 2^(n-16)*(n+8)*(n^7 + 100*n^6 + 3778*n^5 + 68056*n^4 + 606961*n^3 + 2543284*n^2 + 4524300*n + 2575440)/315. - Bruno Berselli, Aug 07 2011

A382615 Expansion of 1/(1 - x/(1 - x)^3)^3.

Original entry on oeis.org

1, 3, 15, 64, 261, 1032, 3982, 15066, 56094, 206068, 748452, 2691966, 9600233, 33982197, 119495229, 417724302, 1452550371, 5026878774, 17321417650, 59450099958, 203306331429, 692955932103, 2354664287943, 7978488379398, 26963061909228, 90897971951727
Offset: 0

Views

Author

Seiichi Manyama, Mar 31 2025

Keywords

Crossrefs

Programs

  • Magma
    R := PowerSeriesRing(Rationals(), 40); f := 1/(1 - x/(1 - x)^3)^3; seq := [ Coefficient(f, n) : n in [0..30] ]; seq;// Vincenzo Librandi, Apr 02 2025
  • Mathematica
    Table[Sum[Binomial[k+2,2]*Binomial[n+2*k-1,n-k],{k,0,n}],{n,0,25}] (* Vincenzo Librandi, Apr 02 2025 *)
  • PARI
    a(n) = sum(k=0, n, binomial(k+2, 2)*binomial(n+2*k-1, n-k));
    

Formula

a(n) = Sum_{k=0..n} binomial(k+2,2) * binomial(n+2*k-1,n-k).
a(n) = 12*a(n-1) - 57*a(n-2) + 139*a(n-3) - 195*a(n-4) + 174*a(n-5) - 102*a(n-6) + 39*a(n-7) - 9*a(n-8) + a(n-9) for n > 9.

A109434 Irregular triangle read by rows: row n contains the numbers from 2^n up to (n+3)*2^(n-2), inclusive, read along their common subdiagonal of A109433.

Original entry on oeis.org

0, 0, 1, 1, 2, 2, 4, 5, 8, 11, 12, 16, 24, 27, 28, 32, 51, 60, 63, 64, 64, 107, 131, 140, 143, 144, 128, 222, 282, 307, 316, 319, 320, 256, 457, 601, 666, 691, 700, 703, 704, 512, 935, 1270, 1432, 1498, 1523, 1532, 1535, 1536, 1024, 1904, 2665, 3057, 3224, 3290
Offset: 0

Views

Author

Robert G. Wilson v, Jun 28 2005

Keywords

Comments

Evolution of 2^n into 2^(n-2)(n+3) as exhibited by A109433.
The forward differences of the last row of the table approache A058396.

Examples

			Triangle begins
   0  0
   1  1
   2  2
   4  5
   8 11 12
  16 24 27 28
  32 51 60 63 64
		

Crossrefs

Programs

  • Mathematica
    T[n_, m_] := Length[ Select[ StringPosition[ #, ToString[(10^m - 1)/9]] & /@ Table[ ToString[ FromDigits[ IntegerDigits[i, 2]]], {i, 2^n, 2^(n + 1) - 1}], # != {} &]]; Join[{0, 0, 1, 1, 2}, Flatten[ Table[ T[n + i, i], {n, 0, 9}, {i, n + 1}]]]

Extensions

New definition from R. J. Mathar, Nov 27 2007

A370478 G.f. satisfies A(x) = ( 1 + x * (A(x)^(1/3) / (1-x))^(3/2) )^3.

Original entry on oeis.org

1, 3, 12, 46, 174, 654, 2451, 9177, 34368, 128826, 483531, 1817673, 6844294, 25815660, 97539435, 369154485, 1399419360, 5313440610, 20205330660, 76946898744, 293443125804, 1120565939780, 4284550682478, 16402204879386, 62864294076480, 241205747620740
Offset: 0

Views

Author

Seiichi Manyama, Mar 31 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec((1+x*((1-sqrt(1-4*x))/(2*x))^3)^3)
    
  • PARI
    a(n, r=3, s=3/2, t=3/2, u=0) = r*sum(k=0, n, binomial(t*k+u*(n-k)+r, k)*binomial(n+(s-1)*k-1, n-k)/(t*k+u*(n-k)+r));

Formula

G.f.: B(x)^3 where B(x) is the g.f. of A071724.
a(n) = 3 * Sum_{k=0..n} binomial(3*k/2+3,k) * binomial(n+k/2-1,n-k)/(3*k/2+3).

A370480 G.f. satisfies A(x) = ( 1 + x * (A(x)^(1/3) / (1-x))^2 )^3.

Original entry on oeis.org

1, 3, 15, 73, 360, 1800, 9112, 46632, 240936, 1255336, 6589080, 34811784, 184990568, 988156872, 5303039256, 28579068520, 154605138984, 839272725864, 4570409517848, 24961191298248, 136688674353000, 750355591919240, 4128471397725336, 22762905189252264
Offset: 0

Views

Author

Seiichi Manyama, Mar 31 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec((1+x*((1-x-sqrt(1-6*x+x^2))/(2*x))^2)^3)
    
  • PARI
    a(n, r=3, s=2, t=2, u=0) = r*sum(k=0, n, binomial(t*k+u*(n-k)+r, k)*binomial(n+(s-1)*k-1, n-k)/(t*k+u*(n-k)+r));

Formula

G.f.: B(x)^3 where B(x) is the g.f. of A006319.
a(n) = 3 * Sum_{k=0..n} binomial(2*k+3,k) * binomial(n+k-1,n-k)/(2*k+3).
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