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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A257635 Triangle with n-th row polynomial equal to Product_{k = 1..n} (x + n + k).

Original entry on oeis.org

1, 2, 1, 12, 7, 1, 120, 74, 15, 1, 1680, 1066, 251, 26, 1, 30240, 19524, 5000, 635, 40, 1, 665280, 434568, 117454, 16815, 1345, 57, 1, 17297280, 11393808, 3197348, 495544, 45815, 2527, 77, 1, 518918400, 343976400, 99236556, 16275700, 1659889, 107800, 4354, 100, 1
Offset: 0

Views

Author

Peter Bala, Nov 05 2015

Keywords

Comments

The row polynomials are a Sheffer sequence. For the associated polynomial sequence of binomial type see A038455.

Examples

			Triangle begins:
[0]       1;
[1]       2,      1;
[2]      12,      7,      1;
[3]     120,     74,     15,     1;
[4]    1680,   1066,    251,    26,    1;
[5]   30240,  19524,   5000,   635,   40,  1;
[6]  665280, 434568, 117454, 16815, 1345, 57, 1;
  ...
		

Crossrefs

Cf. A001813 (column 0), A005449 (first subdiagonal), A098118 (column 1).
Cf. A006963 (row sums), A000407 (alternating row sum).

Programs

  • Maple
    seq(seq(coeff(product(n + x + k, k = 1 .. n), x, i), i = 0..n), n = 0..8);
    # Alternative:
    p := n -> n!*hypergeom([-n, -x + n], [-n], 1):
    seq(seq((-1)^k*coeff(simplify(p(n)), x, k), k=0..n), n=0..6); # Peter Luschny, Nov 27 2021
  • Mathematica
    p[n_, x_] := FunctionExpand[Gamma[2*n + x + 1] / Gamma[n + x + 1]];
    Table[CoefficientList[p[n, x], x], {n,0,8}] // Flatten (* Peter Luschny, Mar 21 2022 *)

Formula

E.g.f.: A(x,t) = B(t)*C(t)^x = 1 + (2 + x)*t + (3 + x)*(4 + x)*t^2/2! + (4 + x)*(5 + x)*(6 + x)*t^3/3! + ..., where B(t) = 1/sqrt(1 - 4*t) is the o.g.f. for A000984 and C(t) = (1 - sqrt(1 - 4*t))/(2*t) is the o.g.f. for A000108.
n-th row polynomial: n!*binomial(2*n + x,n).
T(n, k) = (-1)^k*n!*[x^k] hypergeom([-n, -x + n], [-n], 1). - Peter Luschny, Nov 27 2021
T(n, k) = [x^k] Gamma(2*n + x + 1) / Gamma(n + x + 1). - Peter Luschny, Mar 21 2022

A384136 a(n) = (3*n)!/(2*n)! * Sum_{k=1..n} 1/(2*n+k).

Original entry on oeis.org

1, 11, 191, 4578, 140274, 5238132, 230784840, 11720201616, 674092013040, 43310839531680, 3074579815271040, 238983481496188800, 20187063842072319360, 1841332369689189619200, 180372122189263722009600, 18885338733119777188300800, 2104722524872544008142592000
Offset: 1

Views

Author

Seiichi Manyama, May 20 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n, k*(2*n+1)^(k-1)*abs(stirling(n, k, 1)));

Formula

a(n) = Sum_{k=0..n} k * (2*n+1)^(k-1) * |Stirling1(n,k)|.
a(n) = n! * [x^n] (-log(1 - x)/(1 - x)^(2*n+1)).

A384167 a(n) = 2^n * n! * binomial(3*n/2,n) * Sum_{k=1..n} 1/(n+2*k).

Original entry on oeis.org

1, 10, 143, 2736, 66009, 1926912, 66086271, 2605455360, 116123049585, 5774107852800, 316921177332495, 19032668386099200, 1241454631056114825, 87402945316493721600, 6606130538582006306175, 533534147838972474163200, 45855293972076668267481825, 4178822478568980876361728000
Offset: 1

Views

Author

Seiichi Manyama, May 21 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n, k*(n+2)^(k-1)*2^(n-k)*abs(stirling(n, k, 1)));

Formula

a(n) = Sum_{k=0..n} k * (n+2)^(k-1) * 2^(n-k) * |Stirling1(n,k)|.
a(n) = n! * [x^n] ( -log(1 - 2*x)/(2 * (1 - 2*x)^(n/2+1)) ).

A384168 a(n) = 3^n * n! * binomial(4*n/3,n) * Sum_{k=1..n} 1/(n+3*k).

Original entry on oeis.org

1, 13, 234, 5566, 165944, 5966136, 251491120, 12169996912, 665146831680, 40530954643840, 2724842629685120, 200361647815660800, 15997170878205905920, 1378271357428552115200, 127459020533529062246400, 12593128815600367187507200, 1323895109721239722075136000
Offset: 1

Views

Author

Seiichi Manyama, May 21 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n, k*(n+3)^(k-1)*3^(n-k)*abs(stirling(n, k, 1)));

Formula

a(n) = Sum_{k=0..n} k * (n+3)^(k-1) * 3^(n-k) * |Stirling1(n,k)|.
a(n) = n! * [x^n] ( -log(1 - 3*x)/(3 * (1 - 3*x)^(n/3+1)) ).

A384169 a(n) = 4^n * n! * binomial(5*n/4,n) * Sum_{k=1..n} 1/(n+4*k).

Original entry on oeis.org

1, 16, 347, 9856, 349269, 14885760, 742589175, 42479124480, 2742327328905, 197267905658880, 15649214440432275, 1357388618032742400, 127808331929417605725, 12983375200126773657600, 1415428114244995252270575, 164837363498660501913600000, 20423530465926352502482292625
Offset: 1

Views

Author

Seiichi Manyama, May 21 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n, k*(n+4)^(k-1)*4^(n-k)*abs(stirling(n, k, 1)));

Formula

a(n) = Sum_{k=0..n} k * (n+4)^(k-1) * 4^(n-k) * |Stirling1(n,k)|.
a(n) = n! * [x^n] ( -log(1 - 4*x)/(4 * (1 - 4*x)^(n/4+1)) ).

A253669 Square array read by ascending antidiagonals, T(n, k) = k!*[x^k](log(x+1)*sum(j=0..n, C(2*n,j)*x^j)), n>=0, k>=0.

Original entry on oeis.org

0, 0, 1, 0, 1, -1, 0, 1, 3, 2, 0, 1, 7, -4, -6, 0, 1, 11, 26, 10, 24, 0, 1, 15, 74, -46, -36, -120, 0, 1, 19, 146, 342, 144, 168, 720, 0, 1, 23, 242, 1066, -756, -624, -960, -5040, 0, 1, 27, 362, 2414, 5944, 2844, 3408, 6480, 40320, 0, 1, 31, 506, 4578, 19524
Offset: 0

Views

Author

Peter Luschny, Jan 18 2015

Keywords

Examples

			Square array starts:
[n\k][0   1   2    3     4      5       6]
[0]   0,  1, -1,   2,   -6,    24,   -120, ...
[1]   0,  1,  3,  -4,   10,   -36,    168, ...
[2]   0,  1,  7,  26,  -46,   144,   -624, ...
[3]   0,  1, 11,  74,  342,  -756,   2844, ...
[4]   0,  1, 15, 146, 1066,  5944, -15768, ...
[5]   0,  1, 19, 242, 2414, 19524, 127860, ...
[6]   0,  1, 23, 362, 4578, 48504, 434568, ...
The first few rows as a triangle:
0,
0, 1,
0, 1, -1,
0, 1,  3,   2,
0, 1,  7,  -4,  -6,
0, 1, 11,  26,  10,  24,
0, 1, 15,  74, -46, -36, -120,
0, 1, 19, 146, 342, 144,  168, 720.
		

Crossrefs

Cf. A098118.

Programs

  • Maple
    T := (n,k) -> k!*coeff(series(ln(x+1)*add(binomial(2*n,j)*x^j, j=0..n), x, k+1), x, k): for n from 0 to 6 do lprint(seq(T(n,k), k=0..6)) od;

Formula

T(n,n) = A098118(n).
Previous Showing 11-16 of 16 results.