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 1-5 of 5 results.

A052648 Expansion of e.g.f. 5*x/(1-x).

Original entry on oeis.org

0, 5, 10, 30, 120, 600, 3600, 25200, 201600, 1814400, 18144000, 199584000, 2395008000, 31135104000, 435891456000, 6538371840000, 104613949440000, 1778437140480000, 32011868528640000, 608225502044160000
Offset: 0

Views

Author

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

Keywords

Crossrefs

Cf. A000142, A052849 (k=2), A052560 (k=3), A052578 (k=4).

Programs

  • Maple
    spec := [S,{S=Prod(Sequence(Z),Union(Z,Z,Z,Z,Z))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
  • Mathematica
    With[{nn=20},CoefficientList[Series[(5x)/(1-x),{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, May 01 2016 *)

Formula

E.g.f.: 5*x/(1-x)
Recurrence: {a(0)=0, (-1-n)*a(n)+a(n+1)=0, a(1)=5}
a(n) = 5*n!, n>0.

A159038 a(n) = 8 * n!.

Original entry on oeis.org

8, 16, 48, 192, 960, 5760, 40320, 322560, 2903040, 29030400, 319334400, 3832012800, 49816166400, 697426329600, 10461394944000, 167382319104000, 2845499424768000, 51218989645824000, 973160803270656000
Offset: 1

Views

Author

Zerinvary Lajos, Apr 03 2009

Keywords

Crossrefs

Programs

Formula

a(n) = 8 * A000142(n) for n > 0.

A298881 a(0) = 0; for n>0, a(n) = 6*n!.

Original entry on oeis.org

0, 6, 12, 36, 144, 720, 4320, 30240, 241920, 2177280, 21772800, 239500800, 2874009600, 37362124800, 523069747200, 7846046208000, 125536739328000, 2134124568576000, 38414242234368000, 729870602452992000, 14597412049059840000, 306545653030256640000
Offset: 0

Views

Author

Vincenzo Librandi, Feb 13 2018

Keywords

Crossrefs

Cf. A274266.
Cf. sequences of the type k*n!: A000142 (k=1), A052849 (k=2), A052560 (k=3), A052578 (k=4), A052648 (k=5), this sequence (k=6), A062098 (k=7), A159038 (k=8), A174183 (k=10).

Programs

  • GAP
    Concatenation([0], List([1..25], n -> 6*Factorial(n))); # Bruno Berselli, Feb 13 2018
    
  • Magma
    [n eq 0 select 0 else 6*Factorial(n): n in [0..25]];
    
  • Mathematica
    Join[{0}, 6 Range[25]!]
  • PARI
    a(n) = if (n, 6*n!, 0); \\ Michel Marcus, Feb 15 2018

Formula

E.g.f.: 6*x/(1-x).
a(n) = n*a(n-1) = 6*A000142(n) for n>0.

Extensions

Edited by Bruno Berselli, Feb 13 2018

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).
Showing 1-5 of 5 results.