A003472 -id:A003472 - cp's OEIS frontend

A190051 Expansion of (1-x)(10x^4-20x^3+16x^2-6x+1)/(1-2x)^5.

1, 3, 12, 44, 150, 482, 1476, 4344, 12368, 34240, 92544, 244992, 636928, 1629696, 4111360, 10242048, 25227264, 61505536, 148570112, 355860480, 845807616, 1996095488, 4680056832, 10906763264, 25275924480, 58271465472

Offset: 0

Johannes W. Meijer, May 06 2011

The third left hand column of triangle A175136.

G. C. Greubel, Table of n, a(n) for n = 0..1000 (terms 0..300 from Vincenzo Librandi)
Index entries for linear recurrences with constant coefficients, signature (10,-40,80,-80,32).

Cf. A175136, A011782, A190050.

Related to A003472.

[1] cat [(264 + 214*n + 14*n^3 + 83*n^2 + n^4)*2^(n-7)/3: n in [1..30]]; // G. C. Greubel, Jan 10 2018

A190051:= proc(n) option remember; if n=0 then A190051(n):=1 else A190051(n):= (264+214*n+14*n^3+83*n^2+n^4)*2^(n-7)/3 fi: end: seq (A190051(n), n=0..25);

Join[{1}, LinearRecurrence[{10,-40,80,-80,32}, {3,12,44,150,482}, 30]] (* or *) CoefficientList[Series[(1 - x)*(10*x^4 -20*x^3 +16*x^2 -6*x + 1)/(1 -2*x)^5, {x, 0, 50}], x] (* G. C. Greubel, Jan 10 2018 *)

x='x+O('x^30); Vec((1-x)*(10*x^4-20*x^3+16*x^2-6*x+1)/(1-2*x)^5) \\ G. C. Greubel, Jan 10 2018

for(n=0,30, print1(if(n==0,1,(264 + 214*n + 14*n^3 + 83*n^2 + n^4)*2^(n-7)/3), ", ")) \\ G. C. Greubel, Jan 10 2018

G.f.: (1-x)*(10*x^4-20*x^3+16*x^2-6*x+1)/(1-2*x)^5.
a(n) = (264 + 214*n + 14*n^3 + 83*n^2 + n^4)*2^(n-7)/3 for n >=1 with a(0)=1.
a(n-4) = A003472(n) -7*A003472(n-1) +22*A003472(n-2) -36*A003472(n-3) +30*A003472(n-4) -10*A003472(n-5) for n>=5 with a(0) = 1.

A317495 Triangle read by rows: T(0,0) = 1; T(n,k) =2 * T(n-1,k) + T(n-3,k-1) for k = 0..floor(n/3); T(n,k)=0 for n or k < 0.

Original entry on oeis.org

1, 2, 4, 8, 1, 16, 4, 32, 12, 64, 32, 1, 128, 80, 6, 256, 192, 24, 512, 448, 80, 1, 1024, 1024, 240, 8, 2048, 2304, 672, 40, 4096, 5120, 1792, 160, 1, 8192, 11264, 4608, 560, 10, 16384, 24576, 11520, 1792, 60, 32768, 53248, 28160, 5376, 280, 1, 65536, 114688, 67584, 15360, 1120, 12

Offset: 0

Zagros Lalo, Jul 30 2018

The numbers in rows of the triangle are along a "second layer" of skew diagonals pointing top-left in center-justified triangle given in A013609 ((1+2*x)^n) and along a "second layer" of skew diagonals pointing top-right in center-justified triangle given in A038207 ((2+x)^n), see links. (Note: First layer skew diagonals in center-justified triangles of coefficients in expansions of (1+2*x)^n and (2+x)^n are given in A128099 and A207538 respectively.)
The coefficients in the expansion of 1/(1-2x-x^3) are given by the sequence generated by the row sums.
The row sums give A008998 and Pisot sequences E(4,9), P(4,9) when n > 1, see A020708.
If s(n) is the row sum at n, then the ratio s(n)/s(n-1) is approximately 2.205569430400..., when n approaches infinity.

			Triangle begins:
       1;
       2;
       4;
       8,      1;
      16,      4;
      32,     12;
      64,     32,      1;
     128,     80,      6;
     256,    192,     24;
     512,    448,     80,      1;
    1024,   1024,    240,      8;
    2048,   2304,    672,     40;
    4096,   5120,   1792,    160,     1;
    8192,  11264,   4608,    560,    10;
   16384,  24576,  11520,   1792,    60;
   32768,  53248,  28160,   5376,   280,   1;
   65536, 114688,  67584,  15360,  1120,  12;
  131072, 245760, 159744,  42240,  4032,  84;
  262144, 524288, 372736, 112640, 13440, 448, 1;

Shara Lalo and Zagros Lalo, Polynomial Expansion Theorems and Number Triangles, Zana Publishing, 2018, ISBN: 978-1-9995914-0-3, pp. 358, 359.

Row sums give A008998, A020708.
Cf. A013609
Cf. A038207
Cf. A317494
Cf. A128099, A207538.
Cf. A000079 (column 0), A001787 (column 1), A001788 (column 2), A001789 (column 3), A003472 (column 4).

Flat(List([0..20],n->List([0..Int(n/3)],k->2^(n-3*k)/(Factorial(n-3*k)*Factorial(k))*Factorial(n-2*k)))); # Muniru A Asiru, Jul 31 2018

/* As triangle */ [[2^(n-3*k)/(Factorial(n-3*k)*Factorial(k))* Factorial(n-2*k): k in [0..Floor(n/3)]]: n in [0.. 15]]; // Vincenzo Librandi, Sep 05 2018

t[n_, k_] := t[n, k] = 2^(n - 3k)/((n - 3 k)! k!) (n - 2 k)!; Table[t[n, k], {n, 0, 18}, {k, 0, Floor[n/3]} ]  // Flatten
t[0, 0] = 1; t[n_, k_] := t[n, k] = If[n < 0 || k < 0, 0, 2 t[n - 1, k] + t[n - 3, k - 1]]; Table[t[n, k], {n, 0, 18}, {k, 0, Floor[n/3]}] // Flatten

T(n,k) = 2^(n - 3k) / ((n - 3k)! k!) * (n - 2k)! where n >= 0 and k = 0..floor(n/3).

A372868 Irregular triangle read by rows: T(n,k) is the number of flattened Catalan words of length n with exactly k runs of weak ascents, with 1 <= k <= ceiling(n/2).

Original entry on oeis.org

1, 2, 4, 1, 8, 6, 16, 24, 1, 32, 80, 10, 64, 240, 60, 1, 128, 672, 280, 14, 256, 1792, 1120, 112, 1, 512, 4608, 4032, 672, 18, 1024, 11520, 13440, 3360, 180, 1, 2048, 28160, 42240, 14784, 1320, 22, 4096, 67584, 126720, 59136, 7920, 264, 1, 8192, 159744, 366080, 219648, 41184, 2288, 26

Offset: 1

Stefano Spezia, May 15 2024

With offset 0 for the variable k, T(n,k) is the number of flattened Catalan words of length n with exactly k peaks. In such case, T(4,1) = 6 corresponds to 6 flattened Catalan words of length 4 with 1 peak: 0010, 0100, 0110, 0101, 0120, and 0121. See Baril et al. at page 20.

			The irregular triangle begins:
    1;
    2;
    4,    1;
    8,    6;
   16,   24,    1;
   32,   80,   10;
   64,  240,   60,   1;
  128,  672,  280,  14;
  256, 1792, 1120, 112, 1;
  ...
T(4,2) = 6 since there are 6 flattened Catalan words of length 4 with 2 runs of weak ascents: 0010, 0100, 0101, 0110, 0120, and 0121.

Jean-Luc Baril, Pamela E. Harris, and José L. Ramírez, Flattened Catalan Words, arXiv:2405.05357 [math.CO], 2024. See pp. 8-9.

Cf. A000079, A001788, A002409, A003472, A007051 (row sums), A110654 (row lengths), A140325, A172242.

Cf. A372852, A372972.

T[n_,k_]:=SeriesCoefficient[(1-2x)*x*y/(1-4*x+4*x^2-x^2*y),{x,0,n},{y,0,k}]; Table[T[n,k],{n,14},{k,Ceiling[n/2]}] //Flatten (* or *)
T[n_,k_]:=2^(n-2k+1)Binomial[n-1,2k-2]; Table[T[n,k],{n,14},{k,Ceiling[n/2]}]

G.f.: (1-2*x)*x*y/(1 - 4*x + 4*x^2 - x^2*y).
T(n,k) = 2^(n-2*k+1)*binomial(n-1, 2*k-2).
T(n,1) = A000079(n-1).
T(n,2) = A001788(n-2).
T(n,3) = A003472(n-1).
T(n,4) = A002409(n-7).
T(n,5) = A140325(n-9).
T(n,6) = A172242(n-1).
Sum_{k>=0} T(n,k) = A007051(n-1).

A130749 Triangle A007318*A090181 (as infinite lower triangular matrices) .

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 7, 6, 1, 1, 15, 24, 10, 1, 1, 31, 80, 60, 15, 1, 1, 63, 240, 280, 125, 21, 1, 1, 127, 672, 1120, 770, 231, 28, 1, 1, 255, 1792, 4032, 3920, 1806, 392, 36, 1, 1, 511, 4608, 13440, 17472, 11340, 3780, 624, 45, 1

Offset: 0

Philippe Deléham, Jul 13 2007

			Triangle begins:
  1;
  1,   1;
  1,   3,    1;
  1,   7,    6,     1;
  1,  15,   24,    10,     1;
  1,  31,   80,    60,    15,     1;
  1,  63,  240,   280,   125,    21,    1;
  1, 127,  672,  1120,   770,   231,   28,   1;
  1, 255, 1792,  4032,  3920,  1806,  392,  36,  1;
  1, 511, 4608, 13440, 17472, 11340, 3780, 624, 45,  1;
  ...

Paul Barry, Riordan Pseudo-Involutions, Continued Fractions and Somos 4 Sequences, arXiv:1807.05794 [math.CO], 2018.
Sherry H. F. Yan, Schroeder Paths and Pattern Avoiding Partitions, arXiv:0805.2465 [math.CO], 2008-2009; Corollary 3.6.

Cf. A000012, A000225, A001788, A003472 ; A000012, A000217, A014205.

nmax = 9;
T1[n_, k_] := Binomial[n, k];
T2[n_, k_] := Sum[(-1)^(j-k) Binomial[2n-j, j] Binomial[j, k] CatalanNumber[n-j], {j, 0, n}];
T[n_, k_] := Sum[T1[n, m] T2[m, k], {m, 0, n}];
Table[T[n, k], {n, 0, nmax}, {k, 0, n}] // Flatten (* Jean-François Alcover, Nov 10 2018 *)

N(n, k):=(binomial(n, k-1)*binomial(n, k))/n;
T(n, k):=if k=0 then 1 else sum(binomial(n, i)*N(i, k), i, 1, n); /* Vladimir Kruchinin, Jan 08 2022 */

Sum_{k=0..n} T(n,k) = A007317(n+1).
G.f.: 1/(1-x-xy/(1-x/(1-x-xy/(1-x/(1-x-xy/(1-x.... (continued fraction); [Paul Barry, Jan 12 2009]
T(n,k) = Sum_{i=1..n} binomial(n, i)*N(i,k), T(n,0)=1, where N(n,k) is the triangle of Narayana numbers A001263. - Vladimir Kruchinin, Jan 08 2022

A130813 If X_1,...,X_n is a partition of a 2n-set X into 2-blocks then a(n) is equal to the number of 7-subsets of X containing none of X_i, (i=1,...n).

Original entry on oeis.org

128, 1024, 4608, 15360, 42240, 101376, 219648, 439296, 823680, 1464320, 2489344, 4073472, 6449664, 9922560, 14883840, 21829632, 31380096, 44301312, 61529600, 84198400, 113667840, 151557120, 199779840, 260582400, 336585600, 430829568

Offset: 7

Milan Janjic, Jul 16 2007

nonn

Number of n permutations (n>=7) of 3 objects u,v,z, with repetition allowed, containing n-7 u's. Example: if n=7 then n-7 =(0) zero u, a(1)=128. - Zerinvary Lajos, Aug 05 2008

a(n) is the number of 6-dimensional elements in an n-cross polytope where n>=7. - Patrick J. McNab, Jul 06 2015

Milan Janjic, Two Enumerative Functions
Eric Weisstein's World of Mathematics, Cross Polytope

Cf. A038207, A000079, A001787, A001788, A001789, A003472, A054849, A002409, A054851, A140325, A140354, A046092, A130809, A130810, A130811, A130812. - Zerinvary Lajos, Aug 05 2008

Cf. A000580.

[Binomial(n,n-7)*2^7: n in [7..40]]; // Vincenzo Librandi, Jul 09 2015

a:=n->binomial(2*n,7)+binomial(n,2)*binomial(2*n-4,3)-n*binomial(2*n-2,5)-(2*n-6)*binomial(n,3);
seq(binomial(n,n-7)*2^7,n=7..32); # Zerinvary Lajos, Dec 07 2007
seq(binomial(n+6, 7)*2^7, n=1..22); # Zerinvary Lajos, Aug 05 2008

Table[Binomial[n, n - 7] 2^7, {n, 7, 40}] (* Vincenzo Librandi, Jul 09 2015 *)

a(n) = binomial(2*n,7) + binomial(n,2)*binomial(2*n-4,3) - n*binomial(2*n-2,5) - (2*n-6)*binomial(n,3).
a(n) = C(n,n-7)*2^7, n>=7. - Zerinvary Lajos, Dec 07 2007
G.f.: 128*x^7/(1-x)^8. - Colin Barker, Mar 18 2012
a(n) = 128*A000580(n). a(n+1) = 2*(n+1)*a(n)/(n-6) for n >= 7. - Robert Israel, Jul 08 2015

A213432 a(n) = 2^(n-3)*binomial(n,4).

Original entry on oeis.org

0, 0, 0, 0, 2, 20, 120, 560, 2240, 8064, 26880, 84480, 253440, 732160, 2050048, 5591040, 14909440, 38993920, 100270080, 254017536, 635043840, 1568931840, 3835166720, 9285140480, 22284337152, 53057945600, 125409689600, 294440140800, 687026995200, 1593902628864, 3678236835840, 8446321623040, 19305877995520, 43937515438080, 99591701659648

Offset: 0

N. J. A. Sloane, Jun 11 2012

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

Paolo Xausa, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (10,-40,80,-80,32).

A213432[n_] := 2^(n-3)*Binomial[n, 4]; Array[A213432, 35, 0] (* or *)
LinearRecurrence[{10, -40, 80, -80, 32}, {0, 0, 0, 0, 2}, 35] (* Paolo Xausa, Feb 22 2024 *)

G.f.: -2*x^4 / (2*x-1)^5. - Colin Barker, Jul 22 2013

a(n) = 2*A003472(n). - R. J. Mathar, Jun 18 2014

cp's OEIS Frontend

A190051 Expansion of (1-x)*(10*x^4-20*x^3+16*x^2-6*x+1)/(1-2*x)^5.

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A317495 Triangle read by rows: T(0,0) = 1; T(n,k) =2 * T(n-1,k) + T(n-3,k-1) for k = 0..floor(n/3); T(n,k)=0 for n or k < 0.

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A372868 Irregular triangle read by rows: T(n,k) is the number of flattened Catalan words of length n with exactly k runs of weak ascents, with 1 <= k <= ceiling(n/2).

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A130749 Triangle A007318*A090181 (as infinite lower triangular matrices) .

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A130813 If X_1,...,X_n is a partition of a 2n-set X into 2-blocks then a(n) is equal to the number of 7-subsets of X containing none of X_i, (i=1,...n).

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A213432 a(n) = 2^(n-3)*binomial(n,4).

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A190051 Expansion of (1-x)(10x^4-20x^3+16x^2-6x+1)/(1-2x)^5.