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 1-8 of 8 results.

A090442 Row sums of array A090452 (s2_{3,2}, scaled (3,2)-Stirling2).

Original entry on oeis.org

1, 6, 44, 360, 3152, 28896, 273856, 2661504, 26380544, 265655808, 2710244352, 27952883712, 290977271808, 3053105307648, 32256844087296, 342870535471104, 3664053076557824, 39342496410894336, 424243929700630528, 4592400943255388160, 49885822426526253056
Offset: 1

Views

Author

Wolfdieter Lang, Dec 23 2003

Keywords

Crossrefs

Programs

  • Mathematica
    RecurrenceTable[{(n+1)*a[n] == 6*(2*n-1)*a[n-1] - 4*(n-2)*a[n-2],a[1]==1,a[2]==6},a,{n,20}] (* Vaclav Kotesovec, Oct 14 2012 *)

Formula

a(n) = Sum_{m=2..2*n} A090452(n, m).
Recurrence: (n+1)*a(n) = 6*(2*n-1)*a(n-1) - 4*(n-2)*a(n-2). - Vaclav Kotesovec, Oct 14 2012
a(n) ~ sqrt(4+3*sqrt(2))*(6+4*sqrt(2))^n/(8*sqrt(Pi)*n^(3/2)). - Vaclav Kotesovec, Oct 14 2012
a(n) = 2^(n-1) * A001003(n) = 2^(n-2) * A006318(n). - Jacob Post, Jun 19 2018

A090453 Third column (m=4) of array A090452.

Original entry on oeis.org

2, 16, 51, 118, 230, 402, 651, 996, 1458, 2060, 2827, 3786, 4966, 6398, 8115, 10152, 12546, 15336, 18563, 22270, 26502, 31306, 36731, 42828, 49650, 57252, 65691, 75026, 85318, 96630, 109027, 122576, 137346, 153408, 170835, 189702, 210086
Offset: 0

Views

Author

Wolfdieter Lang, Dec 23 2003

Keywords

Crossrefs

Programs

  • Mathematica
    Table[(n+1)(n^3+15n^2+56n+24)/12,{n,0,40}] (* or *) LinearRecurrence[{5,-10,10,-5,1},{2,16,51,118,230},40] (* Harvey P. Dale, Dec 07 2014 *)

Formula

a(n)= (n+1)*(n^3+15*n^2+56*n+24)/12.
G.f.: (2+6*x-9*x^2+3*x^3)/(1-x)^5.

A091026 Fifth column (m=6) of array A090452.

Original entry on oeis.org

5, 114, 771, 3235, 10365, 27825, 65828, 141552, 282375, 530090, 946275, 1619007, 2671123, 4270245, 6640800, 10078280, 14966001, 21794634, 31184795, 43912995, 60941265, 83450785, 112879860, 150966600, 199796675, 261856530, 340092459
Offset: 0

Views

Author

Wolfdieter Lang, Dec 23 2003

Keywords

Crossrefs

Formula

a(n)= (n+1)*(n+2)*(n^6+45*n^5+745*n^4+5595*n^3+18694*n^2+22440*n+7200)/2880. 2880=8!/(2*7).
G.f.: (5+69*x-75*x^2-20*x^3+60*x^4-30*x^5+5*x^6)/(1-x)^9.

A090454 Fourth column (m=5) of array A090452.

Original entry on oeis.org

15, 105, 396, 1110, 2600, 5390, 10220, 18096, 30345, 48675, 75240, 112710, 164346, 234080, 326600, 447440, 603075, 801021, 1049940, 1359750, 1741740, 2208690, 2774996, 3456800, 4272125, 5241015, 6385680, 7730646, 9302910, 11132100
Offset: 0

Views

Author

Wolfdieter Lang, Dec 23 2003

Keywords

Crossrefs

Formula

a(n)= (n+9)*(n+6)*(n+2)*(n+1)*(n^2+15*n+20)/144,
G.f.: (15-24*x^2+18*x^3-4*x^4)/(1-x)^7.

A091027 Sixth column (m=7) of array A090452.

Original entry on oeis.org

63, 910, 6083, 27483, 97188, 289884, 762048, 1816248, 4001613, 8264718, 16168867, 30204083, 54215070, 93980040, 157979640, 258402312, 412440315, 643939374, 985474539, 1480935379, 2188715144, 3185611044, 4571556360, 6475319760, 9061322985, 12537745038
Offset: 0

Views

Author

Wolfdieter Lang, Dec 23 2003

Keywords

Crossrefs

Cf. A091026.

Programs

  • Mathematica
    LinearRecurrence[{11,-55,165,-330,462,-462,330,-165,55,-11,1},{63,910,6083,27483,97188,289884,762048,1816248,4001613,8264718,16168867},30] (* Harvey P. Dale, Dec 19 2021 *)

Formula

a(n)= (n+12)*(n+9)*(n+3)*(n+2)*(n+1)*(n^5+48*n^4+769*n^3+4782*n^2+11200*n+8400)/86400. 86400=10!/(2*3*7).
G.f.: (63+217*x-462*x^2+225*x^3+80*x^4-120*x^5+45*x^6-6*x^7)/(1-x)^11.

A091029 Signed array used for numerators of generating functions of the column sequences of array A090452.

Original entry on oeis.org

1, 3, -2, 2, 6, -9, 3, 15, 0, -24, 18, -4, 5, 69, -75, -20, 60, -30, 5, 63, 217, -462, 225, 80, -120, 45, -6, 14, 462, 300, -1848, 1785, -525, -210, 210, -63, 7, 252, 2460, -1809, -4932, 8428, -5208, 1050, 448, -336, 84, -8, 42, 2556, 9747, -18775, -2655, 28296, -28182, 12726, -1890, -840, 504, -108, 9
Offset: 2

Views

Author

Wolfdieter Lang, Dec 23 2003

Keywords

Comments

The row polynomials P(m,x) := sum(a(m,k)*x^k,k=0..kmax(m)),m>=2, where kmax(m) := floor(3*m/2)-3=A032766(m-2)=[0,1,3,4,6,7,9,10,...], appear in the numerator of the g.f.s of the columns of A090452.
The sequence of the lengths of the rows is [1,2,4,5,7,8,10,11,13,14,...]=A001651(m-2)= floor((3*m-4)/2).

Examples

			[1]; [3,-2]; [2,6,-9,3]; [15,0,-24,18,-4]; ...
P(3,x)=3-2*x; P(5,x)=15-24*x^2+18*x^3-4*x^4.
		

Formula

a(m, k)=[x^k]P(m, x), with P(m, x) := ((1-x)^(2*m-3))*G(m, x)/x^ceiling(m/2) and the G(m, x) satisfy the hypergeometric differential difference eq. given in A090452.

A091031 Third to last entries in rows of array A090452 (scaled (3,2)-Stirling2).

Original entry on oeis.org

1, 16, 114, 644, 3270, 15642, 72072, 323752, 1428102, 6214520, 26761196, 114287736, 484816540, 2045277990, 8588492100, 35923392720, 149753379270, 622458753840, 2580709189740, 10675646755800, 44074384410420, 181638630107220, 747375951913344, 3070765657798704
Offset: 2

Views

Author

Wolfdieter Lang, Jan 09 2004

Keywords

Crossrefs

Cf. A000108 (last row entries), 3*A002054(n-1) (second to last row entries), A000108, A090452.

Programs

  • Mathematica
    a[n_] := (9*n^2 - 19*n + 8)*(n-1) * CatalanNumber[n]/(4*(2*n-1)); Array[a, 25, 2] (* Amiram Eldar, Aug 30 2025 *)

Formula

a(n) = A090452(n, 2*(n-1)), n>=2.
a(n) = (9*n^2-19*n+8)*(n-1)*C(n)/(4*(2*n-1)), n>=2; with the Catalan numbers C(n) = A000108(n).
a(n) ~ 9 * 2^(2*n-3) * sqrt(n/Pi). - Amiram Eldar, Aug 30 2025

A078740 Triangle of generalized Stirling numbers S_{3,2}(n,k) read by rows (n>=1, 2<=k<=2n).

Original entry on oeis.org

1, 6, 6, 1, 72, 168, 96, 18, 1, 1440, 5760, 6120, 2520, 456, 36, 1, 43200, 259200, 424800, 285120, 92520, 15600, 1380, 60, 1, 1814400, 15120000, 34776000, 33566400, 16304400, 4379760, 682200, 62400, 3270, 90, 1, 101606400, 1117670400
Offset: 1

Views

Author

N. J. A. Sloane, Dec 21 2002

Keywords

Comments

The sequence of row lengths of this array is [1,3,5,7,...] = A005408(n-1), n>=1.
For the scaled array s2_{3,2}(n,k) := a(n,k)*k!/((n+1)!*n!) see A090452.

Examples

			1;
6, 6, 1;
72, 168, 96, 18, 1;
...
		

Crossrefs

Row sums give A078738. Cf. A078739.

Programs

  • Mathematica
    a[n_, k_] := (-1)^k*n!*(n+1)!*HypergeometricPFQ[{2-k, n+1, n+2}, {2, 3}, 1]/(2*(k-2)!); Table[a[n, k], {n, 1, 7}, {k, 2, 2*n}] // Flatten (* Jean-François Alcover, Dec 04 2013 *)

Formula

Recursion: a(n, k) = Sum(binomial(2, p)*fallfac(n-1-p+k, 2-p)*a(n-1, k-p), p=0..2), n>=2, 2<=k<=2*n, a(1, 1)=1, else 0. Rewritten from eq.(19) of the Schork reference with r=3, s=2. fallfac(n, m) := A008279(n, m) (falling factorials triangle).
a(n, k) = (((-1)^k)/k!)*Sum(((-1)^p)*binomial(k, p)*product(fallfac(p+(j-1)*(3-2), 2), j=1..n), p=2..k), n>=1, 2<=k<=2*n, else 0. From eq. (12) of the Blasiak et al. reference with r=3, s=2.
a(n, k) = (-1)^k n! (n+1)! 3F2(2-k, n+1, n+2; 2, 3; 1) / (2(k-2)!). - Jean-François Alcover, Dec 04 2013

Extensions

Edited by Wolfdieter Lang, Dec 23 2003
Showing 1-8 of 8 results.