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.

A293138 E.g.f.: Product_{m>0} (1+x^m+x^(2*m)/2!).

Original entry on oeis.org

1, 1, 3, 12, 72, 480, 3780, 35280, 372960, 4263840, 54432000, 758419200, 11436163200, 185253868800, 3214699488000, 59172265152000, 1163830187520000, 24097823253504000, 525794940582912000, 12073276215576576000, 290883846352619520000, 7318777466097377280000
Offset: 0

Views

Author

Seiichi Manyama, Oct 01 2017

Keywords

Examples

			Let's consider the partitions of n where no positive integer appears more than twice. (See A000726)
For n = 5,
    partition      |                         |
--------------------------------------------------------------------
     5             -> one 5                  -> 1/(1!)       (= 1  )
   = 4 + 1         -> one 4 and one 1        -> 1/(1!*1!)    (= 1  )
   = 3 + 2         -> one 3 and one 2        -> 1/(1!*1!)    (= 1  )
   = 3 + 1 + 1     -> one 3 and two 1        -> 1/(1!*2!)    (= 1/2)
   = 2 + 2 + 1     -> two 2 and one 1        -> 1/(2!*1!)    (= 1/2)
--------------------------------------------------------------------
                                                sum             4
So a(5) = 5! * 4 = 480.
For n = 6,
    partition      |                         |
--------------------------------------------------------------------
     6             -> one 6                  -> 1/(1!)       (= 1  )
   = 5 + 1         -> one 5 and one 1        -> 1/(1!*1!)    (= 1  )
   = 4 + 2         -> one 4 and one 2        -> 1/(1!*1!)    (= 1  )
   = 4 + 1 + 1     -> one 4 and two 1        -> 1/(1!*2!)    (= 1/2)
   = 3 + 3         -> two 3                  -> 1/(2!)       (= 1/2)
   = 3 + 2 + 1     -> one 3, one 2 and one 1 -> 1/(1!*1!*1!) (= 1  )
   = 2 + 2 + 1 + 1 -> two 2 and two 1        -> 1/(2!*2!)    (= 1/4)
--------------------------------------------------------------------
                                                sum            21/4
So a(6) = 6! * 21/4 = 3780.
		

Crossrefs

Column k=2 of A293135.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(b(n-i*j, i-1)/j!, j=0..min(2, n/i))))
        end:
    a:= n-> n!*b(n$2):
    seq(a(n), n=0..23);  # Alois P. Heinz, Oct 02 2017
  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0, Sum[b[n - i j, i - 1]/j!, {j, 0, Min[2, n/i]}]]];
    a[n_] := n! b[n, n];
    a /@ Range[0, 23] (* Jean-François Alcover, Nov 01 2020, after Alois P. Heinz *)

Formula

a(n) ~ c^(1/4) * exp(2*sqrt(c*n) - n) * n^(n+1/2) / (sqrt(5) * n^(3/4)), where c = -polylog(2, -1/2 - I/2) - polylog(2, -1/2 + I/2) = 0.9669456127221570300837545... Equivalently, c = -Sum_{k>=1} (-1)^k * cos(Pi*k/4) / (k^2 * 2^(k/2-1)). - Vaclav Kotesovec, Oct 01 2017

A293139 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f. Product_{i>0} Sum_{j=0..k} (-1)^j*x^(j*i)/j!.

Original entry on oeis.org

1, 1, 0, 1, -1, 0, 1, -1, -2, 0, 1, -1, -1, 0, 0, 1, -1, -1, 0, 0, 0, 1, -1, -1, -1, 0, 120, 0, 1, -1, -1, -1, 0, 0, 0, 0, 1, -1, -1, -1, 1, 20, 180, 5040, 0, 1, -1, -1, -1, 1, 20, 180, 0, 0, 0, 1, -1, -1, -1, 1, 19, 150, 1260, 10080, 0, 0, 1, -1, -1, -1, 1, 19
Offset: 0

Views

Author

Seiichi Manyama, Oct 01 2017

Keywords

Examples

			Square array begins:
   1,   1,  1,  1,  1, ...
   0,  -1, -1, -1, -1, ...
   0,  -2, -1, -1, -1, ...
   0,   0,  0, -1, -1, ...
   0,   0,  0,  0,  1, ...
   0, 120,  0, 20, 20, ...
		

Crossrefs

Columns k=0..2 give A000007, A293140, A293141.
Rows n=0 gives A000012.
Main diagonal gives A293116.
Cf. A293135.

A293486 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f. Product_{i>0} Sum_{j=0..k} x^(j*(2*i-1))/j!.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 6, 0, 1, 1, 1, 6, 24, 0, 1, 1, 1, 7, 24, 120, 0, 1, 1, 1, 7, 24, 180, 720, 0, 1, 1, 1, 7, 25, 180, 1080, 5040, 0, 1, 1, 1, 7, 25, 180, 1200, 10080, 80640, 0, 1, 1, 1, 7, 25, 181, 1200, 10080, 90720, 725760, 0, 1, 1, 1, 7, 25
Offset: 0

Views

Author

Seiichi Manyama, Oct 10 2017

Keywords

Examples

			Square array begins:
   1,   1,   1,   1,   1, ...
   0,   1,   1,   1,   1, ...
   0,   0,   1,   1,   1, ...
   0,   6,   6,   7,   7, ...
   0,  24,  24,  24,  25, ...
   0, 120, 180, 180, 180, ...
		

Crossrefs

Columns k=0..3 give A000007, A293487, A293488, A293489.
Rows n=0 gives A000012.
Main diagonal gives A088009.
Cf. A293135.

A293299 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f. Product_{i>0} 1/(Sum_{j=0..k} x^(j*i)/j!).

Original entry on oeis.org

1, 1, 0, 1, -1, 0, 1, -1, 0, 0, 1, -1, -1, -6, 0, 1, -1, -1, 0, 24, 0, 1, -1, -1, -1, -6, -120, 0, 1, -1, -1, -1, 2, 30, 720, 0, 1, -1, -1, -1, 1, 10, 270, -5040, 0, 1, -1, -1, -1, 1, 20, 170, 0, 80640, 0, 1, -1, -1, -1, 1, 19, 140, 1050, 2520, -725760, 0, 1, -1
Offset: 0

Views

Author

Seiichi Manyama, Oct 05 2017

Keywords

Examples

			Square array begins:
   1,    1,  1,  1,  1, ...
   0,   -1, -1, -1, -1, ...
   0,    0, -1, -1, -1, ...
   0,   -6,  0, -1, -1, ...
   0,   24, -6,  2,  1, ...
   0, -120, 30, 10, 20, ...
		

Crossrefs

Columns k=0..1 give A000007, A293300.
Rows n=0 gives A000012.
Main diagonal gives A293116.

A293301 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f. Product_{i>0} 1/(Sum_{j=0..k} (-1)^j*x^(j*i)/j!).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 4, 0, 1, 1, 3, 18, 0, 1, 1, 3, 12, 120, 0, 1, 1, 3, 13, 66, 840, 0, 1, 1, 3, 13, 74, 450, 7920, 0, 1, 1, 3, 13, 73, 510, 3510, 75600, 0, 1, 1, 3, 13, 73, 500, 4130, 32760, 887040, 0, 1, 1, 3, 13, 73, 501, 4040, 38430, 335160, 10886400, 0, 1, 1, 3
Offset: 0

Views

Author

Seiichi Manyama, Oct 05 2017

Keywords

Examples

			Square array begins:
   1,   1,   1,   1,   1, ...
   0,   1,   1,   1,   1, ...
   0,   4,   3,   3,   3, ...
   0,  18,  12,  13,  13, ...
   0, 120,  66,  74,  73, ...
   0, 840, 450, 510, 500, ...
		

Crossrefs

Columns k=0..2 give A000007, A053529, A293302.
Rows n=0 gives A000012.
Main diagonal gives A000262.

A293195 E.g.f.: Product_{m>0} (1+x^m+x^(2*m)/2!+x^(3*m)/3!).

Original entry on oeis.org

1, 1, 3, 13, 72, 500, 4020, 37380, 389760, 4546080, 58363200, 814968000, 12301027200, 200216016000, 3484710028800, 64639070496000, 1270187702784000, 26414731639296000, 578733086131200000, 13328586071184384000, 321801976039864320000, 8127599117746268160000
Offset: 0

Views

Author

Seiichi Manyama, Oct 02 2017

Keywords

Crossrefs

Column k=3 of A293135.
Cf. A001935.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(b(n-i*j, i-1)/j!, j=0..min(3, n/i))))
        end:
    a:= n-> n!*b(n$2):
    seq(a(n), n=0..23);  # Alois P. Heinz, Oct 02 2017

A293196 E.g.f.: Product_{m>0} (1+x^m+x^(2*m)/2!+x^(3*m)/3!+x^(4*m)/4!).

Original entry on oeis.org

1, 1, 3, 13, 73, 500, 4050, 37590, 393960, 4591440, 58842000, 822729600, 12451546800, 202637635200, 3528601876800, 65440475100000, 1287768658176000, 26788326941376000, 587341833414336000, 13533158213422848000, 326898680478289920000, 8260278864850172160000
Offset: 0

Views

Author

Seiichi Manyama, Oct 02 2017

Keywords

Crossrefs

Column k=4 of A293135.

A293197 E.g.f.: Product_{m>0} (1+x^m+x^(2*m)/2!+x^(3*m)/3!+x^(4*m)/4!+x^(5*m)/5!).

Original entry on oeis.org

1, 1, 3, 13, 73, 501, 4050, 37632, 394296, 4595976, 58932720, 823949280, 12467513520, 202933851120, 3534322952160, 65559527953920, 1290129736896000, 26840074522060800, 588476031700677120, 13560642403296468480, 327603687047488051200, 8278733693718654566400
Offset: 0

Views

Author

Seiichi Manyama, Oct 02 2017

Keywords

Crossrefs

Column k=5 of A293135.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(b(n-i*j, i-1)/j!, j=0..min(5, n/i))))
        end:
    a:= n-> n!*b(n$2):
    seq(a(n), n=0..23);  # Alois P. Heinz, Oct 02 2017
Showing 1-8 of 8 results.