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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A041001 Convolution of A000108(n+1), n >= 0, (Catalan numbers) with A038845 (3-fold convolution of powers of 4).

Original entry on oeis.org

1, 14, 125, 906, 5810, 34364, 191901, 1026610, 5312230, 26767940, 131990066, 639210404, 3048892740, 14354652152, 66828135005, 308078809794, 1408022619806, 6385966846580, 28765327498278, 128777533131500
Offset: 0

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Author

Keywords

Comments

Also convolution of A038836 with A000984 (central binomial coefficients); also convolution of A001791(n+1), n >= 0, with A002802; also convolution of A008549(n+1), n >= 0, with A002697; also convolution of A029760 with A002457; also convolution of A038806(n+1), n >= 0, with A000302 (powers of 4).

Formula

a(n) = (n+3)*(3*(n+6)*2^(2*n+3)-(n+4)*binomial(2*n+7, n+3))/12; G.f. (c(x)^2)/(1-4*x)^3, where c(x) = g.f. for Catalan numbers.

A143376 Triangle read by rows: T(n,k) is the number of unordered pairs of vertices at distance k in the cube Q_n of dimension n (1 <= k <= n).

Original entry on oeis.org

1, 4, 2, 12, 12, 4, 32, 48, 32, 8, 80, 160, 160, 80, 16, 192, 480, 640, 480, 192, 32, 448, 1344, 2240, 2240, 1344, 448, 64, 1024, 3584, 7168, 8960, 7168, 3584, 1024, 128, 2304, 9216, 21504, 32256, 32256, 21504, 9216, 2304, 256, 5120, 23040, 61440, 107520
Offset: 1

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Author

Emeric Deutsch, Sep 05 2008

Keywords

Comments

Sum of entries in row n = 2^(n-1)*(2^n-1) = A006516.
The entries in row n are the coefficients of the Wiener polynomial of the cube Q_n.
Sum_{k=1..n} k*T(n,k) = n*4^(n-1) = A002697(n) = the Wiener index of the cube Q_n.
Triangle T(n,k), 1 <= k <= n, read by rows given by [1,1,0,0,0,0,0,...]DELTA[1,1,0,0,0,0,0,...] where DELTA is the operator defined in A084938; subtriangle of triangle A055372. - Philippe Deléham, Oct 14 2008

Examples

			T(2,1)=4, T(2,2)=2 because in Q_2 (a square) there are 4 distances equal to 1 and 2 distances equal to 2.
Triangle starts:
   1;
   4,   2;
  12,  12,   4;
  32,  48,  32,   8;
  80, 160, 160,  80,  16;
		

Crossrefs

Programs

  • Maple
    T:=proc(n,k) options operator, arrow: 2^(n-1)*binomial(n,k) end proc: for n to 10 do seq(T(n,k),k=1..n) end do; # yields sequence in triangular form
  • Mathematica
    nn = 8; A[u_, z_] := (z + u z)/(1 - (z + u z));
    Drop[Map[Select[#, # > 0 &] &, Map[Drop[#, 1] &,CoefficientList[Series[1/(1 - A[u, z]), {z, 0, nn}], {z, u}]]],1] // Grid (* Geoffrey Critzer, Mar 04 2017 *)
    Flatten[Table[2^(n-1) Binomial[n, k], {n, 10},{k,n}]] (* Indranil Ghosh, Mar 06 2017 *)
  • PARI
    tabl(nn) = {for (n=1, nn, for(k=1, n, print1(2^(n-1) * binomial(n, k),", ");); print();); };
    tabl(10); \\ Indranil Ghosh, Mar 06 2017
    
  • Python
    import math
    f=math.factorial
    def C(n,r): return f(n) / f(r) / f(n-r)
    i=1
    for n in range(1,126):
        for k in range(1,n+1):
            print(str(i)+" "+str(2**(n-1)*C(n,k)))
            i+=1 # Indranil Ghosh, Mar 06 2017

Formula

T(n,k) = 2^(n-1)*binomial(n,k).
G.f.: G(q,z) = qz/((1-2z)(1-2z-2zq)).
T(n,k) = A055372(n,k). - Philippe Deléham, Oct 14 2008

Extensions

Typo corrected by Philippe Deléham, Jan 05 2009

A038697 Convolution of A000917 with A000984 (central binomial coefficients).

Original entry on oeis.org

3, 26, 163, 894, 4558, 22196, 104739, 483062, 2189530, 9789900, 43295118, 189749676, 825364668, 3567219688, 15332925731, 65591312550, 279415474594, 1185903736412, 5016725589402, 21159849864964, 89012979703940
Offset: 0

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Author

Keywords

Comments

Also convolution of A007054 (Super ballot numbers) with A002697;

Crossrefs

Programs

  • Maple
    seq(n*4^(n+1)+binomial(2*n+3,n+1),n=0..30); # Robert Israel, May 22 2019

Formula

a(n) = n*4^(n+1)+binomial(2*n+3, n+1).
G.f.: c(x)*(4-c(x))/(1-4*x)^2, where c(x) = g.f. for Catalan numbers A000108.
(160+64*n)*a(n) - (160+48*n)*a(n+1) + (50+12*n)*a(n+2) - (5+n)*a(n+3)=0. - Robert Israel, May 22 2019

A041005 Convolution of Catalan numbers A000108(n+1), n >= 0, with A020918.

Original entry on oeis.org

1, 16, 159, 1260, 8722, 55152, 326811, 1844084, 10015566, 52754624, 270976342, 1362986520, 6734927460, 32775704608, 157408497171, 747269225028, 3511471892470, 16351481223840, 75525932249922, 346305571781224
Offset: 0

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Author

Keywords

Comments

Also convolution of A001791(n+1), n >= 0, with A038845; also convolution of A008549(n+1), n >= 0, with A002802; also convolution of A029760 with A002697; also convolution of A038806(n+1), n >= 0, with A002457; also convolution of A038836 with A000302 (powers of 4); also convolution of A041001 with A000984 (central binomial coefficients).

Formula

a(n)=binomial(n+7, 3)*binomial(2*(n+4), n+2)/20 - (n+4)*(n+3)*4^(n+1); G.f. (c(x)^2)/(1-4*x)^(7/2), where c(x) = g.f. for Catalan numbers.

A087449 a(n) = n * 4^(n-1) + (2*4^n + 1) / 3.

Original entry on oeis.org

1, 4, 19, 91, 427, 1963, 8875, 39595, 174763, 764587, 3320491, 14330539, 61516459, 262843051, 1118481067, 4742359723, 20043180715, 84467690155, 355050629803, 1488921995947, 6230565890731, 26021775190699, 108485147273899
Offset: 0

Views

Author

Paul Barry, Sep 05 2003

Keywords

Comments

Binomial transform of A064017.

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{9,-24,16},{1,4,19},30] (* Harvey P. Dale, Apr 15 2018 *)
  • PARI
    a(n) = my(p4 = 1<<(2*n)); n * p4 / 4 + (2*p4 + 1) / 3 \\ David A. Corneth, Apr 15 2018

Formula

G.f.: (1-5x+7x^2)/((1-x)(1-4x)^2).
a(n) = A002697(n) + A007583(n).

Extensions

Name clarified by David A. Corneth, Apr 15 2018

A106691 Expansion of g.f. (1+x-2*x^2+x^3+x^4)/((1-x)^2*(1+x)^2*(1+2*x)^2).

Original entry on oeis.org

1, -3, 8, -17, 36, -71, 140, -269, 516, -979, 1852, -3481, 6516, -12127, 22444, -41253, 75236, -135915, 242716, -427185, 737876, -1242743, 2019468, -3106877, 4349636, -4971011, 2485500, 9942071, -49710284, 159072881, -437450388, 1113510059, -2704238684, 6362914533, -14634703396
Offset: 0

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Author

Creighton Dement, May 13 2005

Keywords

Comments

Floretion Algebra Multiplication Program, FAMP Code: 2jbasekrokseq[ - .25'i - .25i' + 'ii' + .25'jk' + .25'kj'], RokType: Y[sqa.Findk()] = Y[sqa.Findk()] - p (internal program code)

Crossrefs

Cf. A002697.

Programs

  • Magma
    [(1/54)*(3*n +4 -27*(-1)^n*(n+4) +(-2)^(n+1)*(3*n-79)): n in [0..40]]; // G. C. Greubel, Sep 09 2021
    
  • Mathematica
    CoefficientList[Series[(1+x-2x^2+x^3+x^4)/((1-x)^2(1+x)^2(1+2x)^2),{x,0,40}],x] (* or *) LinearRecurrence[{-4,-2,8,7,-4,-4},{1,-3,8,-17,36,-71},40] (* Harvey P. Dale, Dec 21 2015 *)
  • SageMath
    [(1/54)*(3*n +4 -27*(-1)^n*(n+4) +(-2)^(n+1)*(3*n-79)) for n in (0..40)] # G. C. Greubel, Sep 09 2021

Formula

From G. C. Greubel, Sep 09 2021: (Start)
a(n) = (1/54)*(3*n +4 -27*(-1)^n*(n+4) +(-2)^(n+1)*(3*n-79)).
E.g.f.: (1/54)*((4 +3*x)*exp(x) -27*(4 -x)*exp(-x) + 2*(79 +6*x)*exp(-2*x)). (End)

A172978 a(n) = binomial(n+10, 10)*4^n.

Original entry on oeis.org

1, 44, 1056, 18304, 256256, 3075072, 32800768, 318636032, 2867724288, 24216338432, 193730707456, 1479398129664, 10848919617536, 76776969601024, 526470648692736, 3509804324618240, 22813728110018560, 144934272698941440, 901813252348968960, 5505807224867389440
Offset: 0

Views

Author

Zerinvary Lajos, Feb 06 2010

Keywords

Crossrefs

Programs

  • Magma
    [Binomial(n+10, 10)*4^n: n in [0..30]]; // Vincenzo Librandi, Jun 06 2011
  • Mathematica
    Table[Binomial[n + 10, 10]*4^n, {n, 0, 20}]

Formula

From Amiram Eldar, Mar 27 2022: (Start)
G.f.: 1/(1 - 4*x)^11.
Sum_{n>=0} 1/a(n) = 14269429/63 - 787320*log(4/3).
Sum_{n>=0} (-1)^n/a(n) = 78125000*log(5/4) - 1098284605/63. (End)

A305833 Triangle read by rows: T(0,0)=1; T(n,k) = 4*T(n-1,k) + T(n-2,k-1) for k = 0..floor(n/2); T(n,k)=0 for n or k < 0.

Original entry on oeis.org

1, 4, 16, 1, 64, 8, 256, 48, 1, 1024, 256, 12, 4096, 1280, 96, 1, 16384, 6144, 640, 16, 65536, 28672, 3840, 160, 1, 262144, 131072, 21504, 1280, 20, 1048576, 589824, 114688, 8960, 240, 1, 4194304, 2621440, 589824, 57344, 2240, 24, 16777216, 11534336, 2949120, 344064, 17920, 336, 1
Offset: 0

Views

Author

Shara Lalo, Jun 11 2018

Keywords

Comments

The numbers in rows of the triangle are along skew diagonals pointing top-left in center-justified triangle given in A013611 ((1+4*x)^n).
The coefficients in the expansion of 1/(1-4x-x^2) are given by the sequence generated by the row sums.
The row sums are A001076 (Denominators of continued fraction convergent to sqrt(5)).
If s(n) is the row sum at n, then the ratio s(n)/s(n-1) is approximately 4.236067977...; a metallic mean (see A098317), when n approaches infinity.

Examples

			Triangle begins:
         1;
         4;
        16,        1;
        64,        8;
       256,       48,        1;
      1024,      256,       12;
      4096,     1280,       96,       1;
     16384,     6144,      640,      16;
     65536,    28672,     3840,     160,      1;
    262144,   131072,    21504,    1280,     20;
   1048576,   589824,   114688,    8960,    240,    1;
   4194304,  2621440,   589824,   57344,   2240,   24;
  16777216, 11534336,  2949120,  344064,  17920,  336,  1;
  67108864, 50331648, 14417920, 1966080, 129024, 3584, 28;
		

References

  • Shara Lalo and Zagros Lalo, Polynomial Expansion Theorems and Number Triangles, Zana Publishing, 2018, ISBN: 978-1-9995914-0-3, pp. 70, 72, 90, 373.

Crossrefs

Row sums give A001076.
Cf. A000302 (column 0), A002697 (column 1), A038845 (column 2), A038846 (column 3), A040075 (column 4).
Cf. A013611.
Cf. A098317.

Programs

  • Mathematica
    t[0, 0] = 1; t[n_, k_] := If[n < 0 || k < 0, 0, 4 t[n - 1, k] + t[n - 2, k - 1]]; Table[t[n, k], {n, 0, 12}, {k, 0, Floor[n/2]}] // Flatten

Formula

G.f.: 1 / (1 - 4*t*x - t^2).

A362353 Triangle read by rows: T(n,k) = (-1)^(n-k)*binomial(n, k)*(k+3)^n, for n >= 0, and k = 0,1, ..., n. Coefficients of certain Sidi polynomials.

Original entry on oeis.org

1, -3, 4, 9, -32, 25, -27, 192, -375, 216, 81, -1024, 3750, -5184, 2401, -243, 5120, -31250, 77760, -84035, 32768, 729, -24576, 234375, -933120, 1764735, -1572864, 531441, -2187, 114688, -1640625, 9797760, -28824005, 44040192, -33480783, 10000000, 6561, -524288, 10937500, -94058496, 403536070, -939524096, 1205308188, -800000000, 214358881
Offset: 0

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Author

Keywords

Comments

This is the member N = 2 of a family of signed triangles with row sums n! = A000142(n): T(N; n, k) = (-1)^(n-k)*binomial(n, k)*(k + N + 1)^n, for integer N, n >= 0 and k = 0, 1, ..., n. The row polynomials PS(N; n, z) = Sum_{k=0..n} T(N; n, k)*z^k = ((-1)^n/z^N)*D_{n,N+1,n}(z) in [Sidi 1980].
For N = -1, 0 and 1 see A258773(n, k), A075513(n+1, k) and (-1)^(n-k) * A154715(n, k), respectively.
The column sequences, for k = 0, 1, ..., 6 and n >= k, are A141413(n+2), (-1)^(n+1)*A018215(n) = 4*(-1)^(n+1)*A002697(n), 5^2*(-1)^n*A081135(n), (-1)^(n+1)*A128964(n-1) = 6^3*(-1)^(n+1)*A081144(n), 7^4*(-1)^n*A139641(n-4), 2^15*(-1)^(n+1)*A173155(n-5), 3^12*(-1)^n*A173191(n-6), respectively.
The e.g.f. of the triangle (see below) needs the exponential convolution (LambertW(-z)/(-z))^2 = Sum_{n>=0} c(2; n)*z^n/n!, where c(2; n) = Sum_{m=0..n} |A137352(n+1, m)|*2^m = A007334(n+2).
The row sums give n! = A000142(n).

Examples

			The triangle T begins:
n\k    0       1        2         3         4          5          6         7
0:     1
1:    -3       4
2:     9     -32       25
3:   -27     192     -375       216
4:    81   -1024     3750     -5184      2401
5:  -243    5120   -31250     77760    -84035      32768
6:   729  -24576   234375   -933120   1764735   -1572864     531441
7: -2187  114688 -1640625   9797760 -28824005   44040192  -33480783  10000000
...
n = 8:  6561 -524288 10937500 -94058496 403536070 -939524096 1205308188 -800000000 2143588,
n = 9: -19683 2359296 -70312500 846526464 -5084554482 16911433728 -32543321076 36000000000 -21221529219 5159780352.
		

Crossrefs

Cf. A000142 (row sums), A075513, A154715, A258773.
Columns k = 0..6 involve (see above): A002697, A007334, A018215, A081135, A081144, A128964, A137352, A139641, A141413, A173155, A173191.

Programs

  • Mathematica
    A362353row[n_]:=Table[(-1)^(n-k)Binomial[n,k](k+3)^n,{k,0,n}];Array[A362353row,10,0] (* Paolo Xausa, Jul 30 2023 *)

Formula

T(n, k) = (-1)^(n-k)*binomial(n, k)*(k + 3)^n, for n >= 0, k = 0, 1, ..., n.
O.g.f. of column k: (x*(k + 3))^k/(1 - (k + 3)*x)^(k+1), for k >= 0.
E.g.f. of column k: exp(-(k + 3)*x)*((k + 3)*x)^k/k!, for k >= 0.
E.g.f. of the triangle, that is, the e.g.f. of its row polynomials {PS(2;n,y)}_{n>=0}): ES(2;y,x) = exp(-3*x)*(1/3)*(d/dz)(W(-z)/(-z))^2, after replacing z by x*y*exp(-x), where W is the Lambert W-function for the principal branch. This becomes ES(2;y,x) = exp(-3*x)*exp(3*(-W(-z)))/(1 - (-W(-z)), with z = x*y*exp(-x).

Extensions

a(41)-a(44) from Paolo Xausa, Jul 31 2023

A368043 Triangle read by rows: T(n, k) = 2^(n + k).

Original entry on oeis.org

1, 2, 4, 4, 8, 16, 8, 16, 32, 64, 16, 32, 64, 128, 256, 32, 64, 128, 256, 512, 1024, 64, 128, 256, 512, 1024, 2048, 4096, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144
Offset: 0

Views

Author

Peter Luschny, Dec 09 2023

Keywords

Examples

			[0]  [  1]
[1]  [  2,   4]
[2]  [  4,   8,  16]
[3]  [  8,  16,  32,    64]
[4]  [ 16,  32,  64,   128,  256]
[5]  [ 32,  64,  128,  256,  512, 1024]
[6]  [ 64, 128,  256,  512, 1024, 2048,  4096]
[7]  [128, 256,  512, 1024, 2048, 4096,  8192, 16384]
[8]  [256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536]
		

Crossrefs

Cf. A000079 (T(n,0)), A004171 (T(n,n-1)), A000302 (T(n,n)), A171476 (row sums), A003683 (alternating row sums), A134353 (antidiagonal sums), A001018 (T(2n, n)), A094014 (T(n, n/2)), A002697.

Programs

  • Mathematica
    Array[2^Range[#,2#]&,10,0] (* Paolo Xausa, Dec 09 2023 *)
  • Python
    from functools import cache
    @cache
    def T_row(n: int) -> list[int]:
        if n == 0: return [1]
        row = T_row(n - 1) + [0]
        for k in range(n): row[k] *= 2
        row[n] = row[n - 1] * 2
        return row
    for n in range(11): print(T_row(n))

Formula

G.f.: 1/((1 - 2*x)*(1 - 4*x*y)). - Stefano Spezia, Dec 09 2023
Previous Showing 31-40 of 49 results. Next