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.

Previous Showing 31-38 of 38 results.

A126776 Basis orbits of n-dimensional cubes.

Original entry on oeis.org

1, 1, 4, 17, 237, 9892
Offset: 1

Views

Author

Jonathan Vos Post, Feb 18 2007

Keywords

Comments

a(7) >= 1456318. [Hughes & Anderson]

Crossrefs

Extensions

Edited by Andrei Zabolotskii, Aug 28 2025

A137320 Coefficients of raising factorial polynomials, T(n,k) = [x^k] p(x, n) where p(x, n) = (m*x + n - 1)*p(x, n - 1) with p[x, 0] = 1, p[x, -1] = 0, p[x, 1] = m*x and m = 2. Triangle read by rows, for n >= 0 and 0 <= k <= n.

Original entry on oeis.org

1, 0, 2, 0, 2, 4, 0, 4, 12, 8, 0, 12, 44, 48, 16, 0, 48, 200, 280, 160, 32, 0, 240, 1096, 1800, 1360, 480, 64, 0, 1440, 7056, 12992, 11760, 5600, 1344, 128, 0, 10080, 52272, 105056, 108304, 62720, 20608, 3584, 256, 0, 80640, 438336, 944992, 1076544, 718368, 290304, 69888, 9216, 512
Offset: 0

Views

Author

Roger L. Bagula, Apr 20 2008

Keywords

Comments

Row sums are factorials.
Also the Bell transform of A052849 (with a(0)=2). For the definition of the Bell transform see A264428. - Peter Luschny, Jan 27 2016

Examples

			[0] {1},
[1] {0, 2},
[2] {0, 2,     4},
[3] {0, 4,     12,     8},
[4] {0, 12,    44,     48,     16},
[5] {0, 48,    200,    280,    160,     32},
[6] {0, 240,   1096,   1800,   1360,    480,    64},
[7] {0, 1440,  7056,   12992,  11760,   5600,   1344,   128},
[8] {0, 10080, 52272,  105056, 108304,  62720,  20608,  3584,  256},
[9] {0, 80640, 438336, 944992, 1076544, 718368, 290304, 69888, 9216, 512}.
		

References

  • Steve Roman, The Umbral Calculus, Dover Publications, New York (1984), pp. 62-63

Crossrefs

Apart from signs, same as A137312.

Programs

  • Maple
    # The function BellMatrix is defined in A264428.
    BellMatrix(n -> `if`(n<2,2,2*n!), 8); # Peter Luschny, Jan 27 2016
    p := (n,x) -> (n + 2*x - 1)!/(2*x - 1)!:
    seq(seq(coeff(expand(p(n,x)), x, k), k=0..n), n=0..9); # Peter Luschny, Feb 26 2019
  • Mathematica
    m = 2; p[x, 0] = 1; p[x, -1] = 0; p[x, 1] = m*x;
    p[x_, n_] := p[x, n] = (m*x + n - 1)*p[x, n - 1];
    Table[CoefficientList[p[x, n], x], {n, 0, 9}] // Flatten
    (* Second program: *)
    BellMatrix[f_, len_] := With[{t = Array[f, len, 0]}, Table[BellY[n, k, t], {n, 0, len - 1}, {k, 0, len - 1}]];
    B = BellMatrix[Function[n, If[n < 2, 2, 2*n!]], rows = 12];
    Table[B[[n, k]], {n, 1, rows}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jun 28 2018, after Peter Luschny *)

Formula

From Peter Luschny, Feb 26 2019: (Start)
p(n, x) = n!*Sum_{k=0..n} (-1)^n*binomial(-x, k)*binomial(-x, n-k).
p(n, x) = (n + 2*x - 1)!/(2*x - 1)!.
T(n, k) = [x^k] p(n,x). (End)

Extensions

Edited and offset set to 0 by Peter Luschny, Feb 26 2019

A281291 Numbers n such that 2*n! is not a refactorable number.

Original entry on oeis.org

2, 4, 8, 16, 256, 65536
Offset: 1

Views

Author

Altug Alkan, Jan 23 2017

Keywords

Comments

See Conjecture 47 and Theorem 51 in Zelinsky's paper for related points.
In Theorem 51 Zelinsky gives a technical result which almost implies that for all sufficiently large n, n! is a refactorable number. (Corrected by Joshua Zelinsky, May 15 2020)
Also note that Luca & Young paper gives a proof for n! is a refactorable number for all n > 5.
This sequence focuses on the 2 * n! and we cannot say that 2 * n! is refactorable for all sufficiently large n at the moment. This is because if 2^(2^k) + 1 is a Fermat prime (A019434), then 2^(2^k) is a term of this sequence and it is not known yet sequence of Fermat primes is finite or not.

Examples

			8 is a term since d(2*8!) = 2^2 * 3^3 does not divide 2 * 8! = 2^8 * 3^2 * 5 * 7.
		

Crossrefs

Programs

A367962 Triangle read by rows. T(n, k) = Sum_{j=0..k} (n!/j!).

Original entry on oeis.org

1, 1, 2, 2, 4, 5, 6, 12, 15, 16, 24, 48, 60, 64, 65, 120, 240, 300, 320, 325, 326, 720, 1440, 1800, 1920, 1950, 1956, 1957, 5040, 10080, 12600, 13440, 13650, 13692, 13699, 13700, 40320, 80640, 100800, 107520, 109200, 109536, 109592, 109600, 109601
Offset: 0

Views

Author

Peter Luschny, Dec 06 2023

Keywords

Examples

			  [0]   1;
  [1]   1,    2;
  [2]   2,    4,    5;
  [3]   6,   12,   15,   16;
  [4]  24,   48,   60,   64,   65;
  [5] 120,  240,  300,  320,  325,  326;
  [6] 720, 1440, 1800, 1920, 1950, 1956, 1957;
		

Crossrefs

Cf. A094587, A000142 (T(n, 0)), A052849 (T(n, 1)), A000522 (T(n, n)), A007526 (T(n,n-1)), A038154 (T(n, n-2)), A355268 (T(n, n/2)), A367963(n) (T(2*n, n)/n!).
Cf. A001339 (row sums), A087208 (alternating row sums), A082030 (accumulated sums), A053482, A331689.

Programs

  • Maple
    T := (n, k) -> add(n!/j!, j = 0..k):
    seq(seq(T(n, k), k = 0..n), n = 0..9);
  • Mathematica
    Module[{n=1},NestList[Append[n#,1+Last[#]n++]&,{1},10]] (* or *)
    Table[Sum[n!/j!,{j,0,k}],{n,0,10},{k,0,n}] (* Paolo Xausa, Dec 07 2023 *)
  • Python
    from functools import cache
    @cache
    def a_row(n: int) -> list[int]:
        if n == 0: return [1]
        row = a_row(n - 1) + [0]
        for k in range(n): row[k] *= n
        row[n] = row[n - 1] + 1
        return row
  • SageMath
    def T(n, k): return sum(falling_factorial(n, n - j) for j in range(k + 1))
    for n in range(9): print([T(n, k) for k in range(n + 1)])
    

Formula

T(n, k) = A094587(n, k) * A000522(k).
T(n, k) = e * (n! / k!) * Gamma(k + 1, 1).
Sum_{k=0..n} T(n, k) * 2^(n - k) = A053482(n).
Sum_{k=0..n} T(n, k) * binomial(n, k) = A331689(n).
Recurrence: T(n, n) = T(n, n-1) + 1 starting with T(0, 0) = 1.
For k <> n: T(n, k) = n * T(n-1, k).

A371740 Triangle read by rows: g.f. (1 - t)^(-x) * (1 + t)^(2-x).

Original entry on oeis.org

1, 2, 1, 1, 0, 4, 0, 3, 1, 0, 6, 6, 0, 5, 6, 1, 0, 16, 24, 8, 0, 14, 23, 10, 1, 0, 60, 110, 60, 10, 0, 54, 105, 65, 15, 1, 0, 288, 600, 420, 120, 12, 0, 264, 574, 435, 145, 21, 1, 0, 1680, 3836, 3150, 1190, 210, 14, 0, 1560, 3682, 3199, 1330, 280, 28, 1, 0, 11520, 28224, 25984, 11760, 2800, 336, 16
Offset: 0

Views

Author

Peter Bala, Apr 09 2024

Keywords

Examples

			Triangle begins
 n\k |  0    1     2    3    4   5
 - - - - - - - - - - - - - - - - -
  0  |  1
  1  |  2
  2  |  1    1
  3  |  0    4
  4  |  0    3     1
  5  |  0    6     6
  6  |  0    5     6    1
  7  |  0   16    24    8
  8  |  0   14    23   10    1
  9  |  0   60   110   60   10
 10  |  0   54   105   65   15   1
 ...
		

Crossrefs

Programs

  • Maple
    with(combinat):
    T := proc (n, k); if irem(n, 2) = 0 then abs(Stirling1((1/2)*n, k)) + (n/2)*abs(Stirling1((n-2)/2, k)) else (n+1)*abs(Stirling1((n-1)/2, k)) end if; end proc:
    seq(print(seq(T(n, k), k = 0..floor(n/2))), n = 0..12);

Formula

G.f.: (1 - t)^(-x)*(1 + t)^(2-x) = Sum_{n >= 0} R(n, x)*t^n/floor((n+1)/2)! = 1 + 2*t/1! + (1 + x)*t^2/1! + 4*x*t^3/2! + x*(3 + x)*t^4/2! + 6*x*(1 + x)*t^5/3! + x*(1 + x)*(5 + x)*t^6/3! + 8*x*(1 + x)*(2 + x)*t^7/3! + x*(1 + x)*(2 + x)*(7 + x)*t^8/4! + 10*x*(1 + x)*(2 + x)*(3 + x)*t^9/5! + ....
Row polynomials: R(2*n, x) = (2*n - 1 + x) * Product_{i = 0..n-2} (x + i) for n >= 1.
R(2*n+1, x) = (2*n + 2) * Product_{i = 0..n-1} (x + i) for n >= 0.
T(2*n, k) = |Stirling1(n, k)| + n*|Stirling1(n-1, k)| = A132393(n, k) + n* A132393(n-1, k);
T(2*n+1, k) = (2*n + 2)*|Stirling1(n, k)| = (2*n + 2)*A132393(n, k).
n-th row sum equals 2 * floor((n+1)/2)! for n >= 1.

A384494 Triangle read by rows: T(n, k) = (-1)^k*(k+1)*(n+1-k)!, n >= 0, k = 0..n.

Original entry on oeis.org

1, 2, -2, 6, -4, 3, 24, -12, 6, -4, 120, -48, 18, -8, 5, 720, -240, 72, -24, 10, -6, 5040, -1440, 360, -96, 30, -12, 7, 40320, -10080, 2160, -480, 120, -36, 14, -8, 362880, -80640, 15120, -2880, 600, -144, 42, -16, 9, 3628800, -725760, 120960, -20160, 3600, -720, 168, -48, 18, -10
Offset: 0

Views

Author

Wolfdieter Lang, May 31 2025

Keywords

Comments

This triangle, written as (infinite) square matrix MT with vanishing upper diagonals 0, together with the Riordan triangle A104698, written also as such a square matrix MR, appears in the double sum formula for the number of certain restricted permutations given in A086852(n), as diagonal sequence A086852(n+2) = (2*MR*MT^t)_{n,n}, for n >=0, where t indicates matrix transpositon.

Examples

			The triangle T begins:
  n\k        0        1       2       3     4     5   6   7  8    9 ...
  ---------------------------------------------------------------------
  0:         1
  1:         2       -2
  2:         6       -4       3
  3:        24      -12       6      -4
  4:       120      -48      18      -8     5
  5:       720     -240      72     -24    10    -6
  6:      5040    -1440     360     -96    30   -12   7
  7:     40320   -10080    2160    -480    12   -36  14  -8
  8:    362880   -80640   15120   -2880   600  -144  42 -16  9
  9:   3628800  -725760  120960  -20160  3600  -720 168 -48 18 -10
  ...
		

Crossrefs

Column sequences: A000142(n+1), -A052849, A052560(n-1), -A052578(n-2), A052648(n-3), -A298881(n-4), A062098(n-5), -A159038(n-6), ...

Programs

  • Mathematica
    Table[(-1)^k * (k+1) * (n+1-k)!, {n, 0, 9}, {k, 0, n}] // Flatten (* Amiram Eldar, May 31 2025 *)

Formula

T(n, k) = (-1)^k*(k+1)*(n+1-k)!, for n >= 0 and k = 0, 1, ..., n.
O.g.f. of row polynomials P(n, y) := Sum_{k=0..n} T(n, k) y^k: G(x, y) = ((N(x) - 1)/x) * (1/(1 + y*x)^2), with N(x) = hypergeometric([1,1], [], x), the o.g.f. of {n!}_{n>=0} (see A000142).

A117826 First four terms of the sequence are doubled, then those numbers are tripled and then those numbers are quadrupled, etc.

Original entry on oeis.org

1, 2, 3, 4, 2, 4, 6, 8, 6, 12, 18, 24, 24, 48, 72, 96, 120, 240, 360, 480, 720, 1440, 2160, 2880, 5040, 10080, 15120, 20160, 40320, 80640, 120960, 161280, 362880, 725760, 1088640, 1451520, 3628800, 7257600, 10886400, 14515200, 39916800, 79833600
Offset: 1

Views

Author

Robert G. Wilson v, Apr 25 2006

Keywords

Crossrefs

Programs

  • Mathematica
    Table[n!{1, 2, 3, 4}, {n, 11}] // Flatten

Formula

a(4n-3) = A000142(n). a(4n-2)=2*A000142(n)=A052849(n), a(4n-1)=3*A000142(n)=A052560(n), a(4n)=4*A000142(n)=2*A052849(n)=A052578(n).

A260229 a(n) = floor(e^(n!)).

Original entry on oeis.org

2, 7, 403, 26489122129, 13041808783936322797338790280986488113446079415755132
Offset: 1

Views

Author

Ilya Gutkovskiy, Jul 20 2015

Keywords

Comments

The exponential growth in the number of permutations of n elements.
Next term is too big to be included.

Examples

			a(1) = floor(e^(1!)) = floor(e) = 2.
		

Crossrefs

Programs

  • Mathematica
    Table[Floor[E^n!], {n, 1, 7}]
  • PARI
    default(realprecision, 100); vector(5, n, floor(exp(n!))) \\ Michel Marcus, Aug 06 2015

Formula

a(n) = A000149(A000142(n)).
a(n) = floor(sqrt(e^A052849(n) - e^A000142(n) + sqrt(e^A052849(n) - e^A000142(n) + sqrt(e^A052849(n) - e^A000142(n) + ...)))).
Previous Showing 31-38 of 38 results.