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.

A055585 Second column of triangle A055584.

Original entry on oeis.org

1, 6, 25, 88, 280, 832, 2352, 6400, 16896, 43520, 109824, 272384, 665600, 1605632, 3829760, 9043968, 21168128, 49152000, 113311744, 259522560, 590872576, 1337982976, 3014656000, 6761218048, 15099494400, 33587986432, 74440507392
Offset: 0

Views

Author

Wolfdieter Lang, May 26 2000

Keywords

Comments

Number of 132-avoiding permutations of [n+5] containing exactly three 123 patterns. - Emeric Deutsch, Jul 13 2001
If X_1,X_2,...,X_n are 2-blocks of a (2n+2)-set X then, for n>=1, a(n-1) is the number of (n+3)-subsets of X intersecting each X_i, (i=1,2,...,n). - Milan Janjic, Nov 18 2007
Convolution of A001792 with itself. - Philippe Deléham, Feb 21 2013

Examples

			a(1)=6 because 432516,432561,435126,452136,532146 and 632145 are the only 132-avoiding permutations of 123456, containing exactly three increasing subsequences of length 3.
		

Crossrefs

Cf. A055584, partial sums of A049612, n >= 1.

Programs

  • Mathematica
    Table[(1/3)*2^(n-3)*(n+1)*(n+3)*(n+8), {n,0,50}] (* G. C. Greubel, Aug 22 2015 *)
    LinearRecurrence[{8,-24,32,-16},{1,6,25,88},30] (* Harvey P. Dale, Nov 03 2017 *)
  • PARI
    Vec(((1-x)^2)/(1-2*x)^4 + O(x^30)) \\ Michel Marcus, Aug 22 2015

Formula

G.f.: (1-x)^2/(1-2*x)^4.
a(n) = A055584(n+1, 1). a(n) = sum(a(j), j=0..n-1)+A001793(n+1), n >= 1.
a(n) = 2^(n-3)(n+1)(n+3)(n+8)/3.
Preceded by 0, this is the binomial transform of the tetrahedral numbers A000292. - Carl Najafi, Sep 08 2011
E.g.f.: (1/6)*(2*x^3 + 15*x^2 + 24*x + 6)*exp(2*x). - G. C. Greubel, Aug 22 2015

A055586 Sixth column of triangle A055584.

Original entry on oeis.org

1, 10, 59, 268, 1037, 3598, 11535, 34832, 100369, 278546, 749587, 1966100, 5046293, 12714006, 31522839, 77070360, 186122265, 444596250, 1051721755, 2466250780, 5737807901, 13254000670, 30417092639, 69390565408
Offset: 0

Views

Author

Wolfdieter Lang, May 26 2000

Keywords

Crossrefs

Cf. A055584.
Partial sums of A027608.

Programs

  • Mathematica
    CoefficientList[Series[1/(((1-x)^2)(1-2x)^4),{x,0,30}],x] (* or *) LinearRecurrence[{10,-41,88,-104,64,-16},{1,10,59,268,1037,3598},30] (* Harvey P. Dale, Jul 31 2025 *)
  • PARI
    Vec(1/(((1-x)^2)*(1-2*x)^4) + O(x^40)) \\ Michel Marcus, Dec 11 2015

Formula

G.f.: 1/(((1-x)^2)*(1-2*x)^4).
a(n) = A055584(n+5, 5).
a(n) = Sum_{j=0..n-1} a(j) + A055582(n) for n >= 1.
E.g.f.: exp(x)*(x + 9) + 8*exp(2*x)*(2*x^3 + 3*x^2 + 6*x - 3)/3. - Stefano Spezia, Sep 24 2024

A049612 a(n) = T(n,3), array T as in A049600.

Original entry on oeis.org

0, 1, 5, 19, 63, 192, 552, 1520, 4048, 10496, 26624, 66304, 162560, 393216, 940032, 2224128, 5214208, 12124160, 27983872, 64159744, 146210816, 331350016, 747110400, 1676673024, 3746562048, 8338276352, 18488492032
Offset: 0

Views

Author

Keywords

Comments

If X_1, X_2, ..., X_n are 2-blocks of a (2n+3)-set X then, for n >= 1, a(n+1) is the number of (n+3)-subsets of X intersecting each X_i, (i=1,2,...,n). - Milan Janjic, Nov 18 2007

References

  • Robert Cori, Gabor Hetyei, Genus one partitions, in 26th International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC 2014), 2014, Chicago, United States. Discrete Mathematics and Theoretical Computer Science, DMTCS Proceedings vol. AT, pp. 333-344,

Crossrefs

Cf. A049600.
Row sums of triangle A055252. a(n+1) = A055584(n, 0), n >= 0.

Programs

  • Mathematica
    CoefficientList[Series[x (1-x)^3/(1-2x)^4,{x,0,30}],x] (* or *) Join[ {0},LinearRecurrence[{8,-24,32,-16},{1,5,19,63},30]] (* Harvey P. Dale, Jan 07 2014 *)

Formula

G.f.: x*(1-x)^3 /(1-2*x)^4.
a(n) = Sum_{k=0..floor((n+3)/2)} C(n+3, 2k)*C(k+1, 3). - Paul Barry, May 15 2003
a(n+1) = 2^n*n^3/48 + 5*2^n*n^2/16 + 7*2^n*n/6 + 2^n, n>=1. - Milan Janjic, Nov 18 2007
Binomial transform of the tetrahedral numbers A000292 when omitting the initial 0 in both sequences. - Carl Najafi, Sep 08 2011

A055252 Triangle of partial row sums (prs) of triangle A055249.

Original entry on oeis.org

1, 4, 1, 13, 5, 1, 38, 18, 6, 1, 104, 56, 24, 7, 1, 272, 160, 80, 31, 8, 1, 688, 432, 240, 111, 39, 9, 1, 1696, 1120, 672, 351, 150, 48, 10, 1, 4096, 2816, 1792, 1023, 501, 198, 58, 11, 1, 9728, 6912, 4608, 2815, 1524, 699, 256, 69, 12, 1, 22784, 16640, 11520
Offset: 0

Views

Author

Wolfdieter Lang, May 26 2000

Keywords

Comments

In the language of the Shapiro et al. reference (given in A053121) such a lower triangular (ordinary) convolution array, considered as matrix, belongs to the Riordan-group. The G.f. for the row polynomials p(n,x) (increasing powers of x) is (((1-z)^2)/(1-2*z)^3)/(1-x*z/(1-z)).
This is the third member of the family of Riordan-type matrices obtained from A007318(n,m) (Pascal's triangle read as lower triangular matrix) by repeated application of the prs-procedure.
The column sequences appear as A049611(n+1), A001793, A001788, A055580, A055581, A055582, A055583 for m=0..6.

Examples

			[0] 1
[1] 4, 1
[2] 13, 5, 1
[3] 38, 18, 6, 1
[4] 104, 56, 24, 7, 1
[5] 272, 160, 80, 31, 8, 1
[6] 688, 432, 240, 111, 39, 9, 1
[7] 1696, 1120, 672, 351, 150, 48, 10, 1
Fourth row polynomial (n = 3): p(3, x) = 38 + 18*x + 6*x^2 + x^3.
		

Crossrefs

Cf. A007318, A055248, A055249. Row sums: A049612(n+1)= A055584(n, 0).

Programs

  • Maple
    T := (n, k) -> binomial(n, k)*hypergeom([3, k - n], [k + 1], -1):
    for n from 0 to 7 do seq(simplify(T(n, k)), k = 0..n) od; # Peter Luschny, Sep 23 2024

Formula

a(n, m)=sum(A055249(n, k), k=m..n), n >= m >= 0, a(n, m) := 0 if n
Column m recursion: a(n, m)= sum(a(j, m), j=m..n-1)+ A055249(n, m), n >= m >= 0, a(n, m) := 0 if n
G.f. for column m: (((1-x)^2)/(1-2*x)^3)*(x/(1-x))^m, m >= 0.
T(n, k) = binomial(n, k)*hypergeom([3, k - n], [k + 1], -1). - Peter Luschny, Sep 23 2024

A055587 Triangle with columns built from row sums of the partial row sums triangles obtained from Pascal's triangle A007318. Essentially A049600 formatted differently.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 4, 3, 1, 1, 8, 8, 4, 1, 1, 16, 20, 13, 5, 1, 1, 32, 48, 38, 19, 6, 1, 1, 64, 112, 104, 63, 26, 7, 1, 1, 128, 256, 272, 192, 96, 34, 8, 1, 1, 256, 576, 688, 552, 321, 138, 43, 9, 1, 1, 512, 1280, 1696, 1520, 1002, 501, 190, 53, 10, 1, 1, 1024, 2816, 4096
Offset: 0

Author

Wolfdieter Lang, May 30 2000

Keywords

Comments

In the language of the Shapiro et al. reference (given in A053121) such a lower triangular (ordinary) convolution array, considered as matrix, belongs to the Riordan-group. The G.f. for the row polynomials p(n,x) (increasing powers of x) is 1/((1-z)*(1-x*z*(1-z)/(1-2*z))).
Column m (without leading zeros) is obtained from convolution of A000012 (powers of 1) with m-fold convoluted A011782.

Examples

			{1}; {1, 1}; {1, 2, 1}; {1, 4, 3, 1}; {1, 8, 8, 4, 1}; ...
Fourth row polynomial (n=3): p(3,x)= 1+4*x+3*x^2+x^3
		

Crossrefs

Cf. A049600, column sequences are A000012 (powers of 1), A000079 (powers of 2), A001792, A049611, A049612, A055589, A055852-5 for m=0..9, row sums: A055588.

Programs

  • Mathematica
    t[n_, k_] := Hypergeometric2F1[k, k-n, 1, -1]; Table[t[n, k], {n, 0, 11}, {k, 0, n}] // Flatten (* Jean-François Alcover, Mar 05 2014, after Paul D. Hanna *)
  • PARI
    {T(n,k) = if( n<0 || k<0, 0, polcoeff( polcoeff( 1 / ((1 - z) * (1 - x*z * (1 - z) / (1 - 2*z) + z * O(z^n) + x * O(x^k))), k), n))}; /* Michael Somos, Sep 30 2003 */
    
  • PARI
    {T(n,k)=if(k>n||n<0||k<0,0,if(k==0||k==n,1, sum(j=0,n-k,binomial(n-k,j)*binomial(k+j-1,k-1)););)} (Hanna)

Formula

a(n, m)= Am(n, 0) if n >= m >= 0 and a(n, m) := 0 if nA007318) with the lower triangular matrix A007318 (Pascal triangle) and prs^(m) is the partial row sums (prs) mapping for triangular matrices applied m times. See e.g. A055584 for m=4.
G.f. for column m: (1/(1-x))*(x*(1-x)/(1-2*x))^m, m >= 0.
T(n, k) = sum_{j=0..n-k} C(n-k, j)*C(k+j-1, k-1). - Paul D. Hanna, Jan 14 2004

A055855 Convolution of A055854 with A011782.

Original entry on oeis.org

0, 1, 10, 64, 328, 1462, 5908, 22180, 78592, 265729, 864146, 2719028, 8316200, 24814832, 72453344, 207502016, 584094080, 1618757120, 4423347200, 11932579840, 31812874240, 83901227008, 219074805760, 566754967552
Offset: 0

Author

Wolfdieter Lang May 30 2000

Keywords

Comments

Tenth column of triangle A055587.
T(n,8) of array T as in A049600.

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 30); [0] cat Coefficients(R!( x*(1-x)^8/(1-2*x)^9 )); // G. C. Greubel, Jan 16 2020
    
  • Maple
    seq(coeff(series(x*(1-x)^8/(1-2*x)^9, x, n+1), x, n), n = 0..30); # G. C. Greubel, Jan 16 2020
  • Mathematica
    CoefficientList[Series[x*(1-x)^8/(1-2*x)^9, {x,0,30}], x] (* G. C. Greubel, Jan 16 2020 *)
  • PARI
    my(x='x+O('x^30)); concat([0], Vec(x*(1-x)^8/(1-2*x)^9)) \\ G. C. Greubel, Jan 16 2020
    
  • Sage
    def A055855_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( x*(1-x)^8/(1-2*x)^9 ).list()
    A055855_list(30) # G. C. Greubel, Jan 16 2020

Formula

a(n) = T(n, 8) = A055587(n+8, 9).
G.f.: x*(1-x)^8/(1-2*x)^9.
Showing 1-6 of 6 results.