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 1-6 of 6 results.

A293071 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of g.f. Product_{i>0} Sum_{j=0..k} (-1)^j*j!*x^(j*i).

Original entry on oeis.org

1, 1, 0, 1, -1, 0, 1, -1, -1, 0, 1, -1, 1, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, -6, 0, 1, 0, 1, -1, 1, -6, 0, -3, 0, 0, 1, -1, 1, -6, 24, 3, 4, 1, 0, 1, -1, 1, -6, 24, 3, 4, -3, 0, 0, 1, -1, 1, -6, 24, -117, -20, -3, 4, 0, 0, 1, -1, 1, -6, 24, -117, -20, -27, -8, -2
Offset: 0

Views

Author

Seiichi Manyama, Oct 03 2017

Keywords

Examples

			Square array begins:
   1,  1,  1,  1,  1, ...
   0, -1, -1, -1, -1, ...
   0, -1,  1,  1,  1, ...
   0,  0,  0, -6, -6, ...
   0,  0,  0,  0, 24, ...
   0,  1, -3,  3,  3, ...
		

Crossrefs

Columns k=0..5 give A000007, A010815, A293072, A293255, A293256, A293257.
Rows n=0 gives A000012.
Main diagonal gives A293236.
Cf. A293202.

Programs

  • Mathematica
    nmax = 12;
    col[k_] := CoefficientList[Product[Sum[(-1)^j j! x^(i j), {j, 0, k}], {i, 1, nmax+1}] + O[x]^(nmax+1), x]; M = PadRight[col[#], nmax+1]& /@ Range[0, nmax] // Transpose;
    A[n_, k_] := M[[n+1, k+1]];
    Table[A[n-k, k], {n, 0, nmax}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Nov 15 2020 *)

A293204 G.f.: Product_{m>0} (1+x^m+2!*x^(2*m)).

Original entry on oeis.org

1, 1, 3, 2, 6, 7, 12, 13, 22, 26, 42, 46, 73, 80, 116, 139, 194, 226, 306, 358, 482, 558, 735, 856, 1108, 1300, 1657, 1926, 2426, 2834, 3530, 4110, 5082, 5898, 7234, 8409, 10216, 11860, 14304, 16568, 19891, 22990, 27470, 31670, 37630, 43382, 51274, 58982, 69450
Offset: 0

Views

Author

Seiichi Manyama, Oct 02 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)
   = 4 + 1         -> one 4 and one 1        -> 1!*1!    (= 1)
   = 3 + 2         -> one 3 and one 2        -> 1!*1!    (= 1)
   = 3 + 1 + 1     -> one 3 and two 1        -> 1!*2!    (= 2)
   = 2 + 2 + 1     -> two 2 and one 1        -> 2!*1!    (= 2)
--------------------------------------------------------------
                                                a(5)      = 7.
For n = 6,
    partition      |                         |
--------------------------------------------------------------
     6             -> one 6                  -> 1!       (= 1)
   = 5 + 1         -> one 5 and one 1        -> 1!*1!    (= 1)
   = 4 + 2         -> one 4 and one 2        -> 1!*1!    (= 1)
   = 4 + 1 + 1     -> one 4 and two 1        -> 1!*2!    (= 2)
   = 3 + 3         -> two 3                  -> 2!       (= 2)
   = 3 + 2 + 1     -> one 3, one 2 and one 1 -> 1!*1!*1! (= 1)
   = 2 + 2 + 1 + 1 -> two 2 and two 1        -> 2!*2!    (= 4)
--------------------------------------------------------------
                                                a(6)      = 12.
		

Crossrefs

Column k=2 of A293202.
Cf. A293072.

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-> b(n$2):
    seq(a(n), n=0..50);  # Alois P. Heinz, Oct 02 2017
  • Mathematica
    nmax = 100; CoefficientList[Series[Product[1 + x^k + 2*x^(2*k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Oct 02 2017 *)

Formula

a(n) ~ c^(1/4) * exp(2*sqrt(c*n)) / (4 * sqrt(Pi) * n^(3/4)), where c = Pi^2/3 - arctan(sqrt(7))^2 + log(2)^2/4 + polylog(2, -1/4 - I*sqrt(7)/4) + polylog(2, -1/4 + I*sqrt(7)/4) = 1.323865936864425754643630663383779192757247984691212163137... - Vaclav Kotesovec, Oct 02 2017
Equivalently, c = -polylog(2, -1/2 + I*sqrt(7)/2) - polylog(2, -1/2 - I*sqrt(7)/2). - Vaclav Kotesovec, Oct 05 2017

A289485 G.f.: Product_{m>0} (1 + x^m + 2!*x^(2*m) + 3!*x^(3*m)).

Original entry on oeis.org

1, 1, 3, 8, 6, 13, 24, 37, 46, 98, 90, 142, 235, 296, 392, 601, 746, 1018, 1428, 1702, 2258, 3132, 3891, 5044, 6766, 8134, 10681, 13812, 16952, 20996, 27986, 33144, 41376, 52500, 64066, 79401, 99718, 119590, 147162, 181880, 220339, 266662, 329342, 391736
Offset: 0

Views

Author

Seiichi Manyama, Oct 03 2017

Keywords

Crossrefs

Column k=3 of A293202.

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-> b(n$2):
    seq(a(n), n=0..50);  # Alois P. Heinz, Oct 04 2017
  • PARI
    Vec(prod(m=1, 50, 1+x^m+2*x^(2*m)+6*x^(3*m)) + O(x^50)) \\ Michel Marcus, Oct 04 2017

A289486 G.f.: Product_{m>0} (1 + x^m + 2!*x^(2*m) + 3!*x^(3*m) + 4!*x^(4*m)).

Original entry on oeis.org

1, 1, 3, 8, 30, 13, 48, 61, 142, 170, 378, 430, 1099, 872, 1304, 2305, 3626, 4042, 6900, 8086, 13634, 17628, 24915, 29524, 53998, 51718, 74953, 96996, 150104, 172292, 234938, 296472, 416064, 504132, 690826, 812625, 1184134, 1378774, 1823778, 2264576, 3115051
Offset: 0

Views

Author

Seiichi Manyama, Oct 03 2017

Keywords

Crossrefs

Column k=4 of A293202.

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(4, n/i))))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..50);  # Alois P. Heinz, Oct 04 2017

A293250 G.f.: Product_{m>0} (1 + x^m + 2!*x^(2*m) + 3!*x^(3*m) + 4!*x^(4*m) + 5!*x^(5*m)).

Original entry on oeis.org

1, 1, 3, 8, 30, 133, 48, 181, 262, 530, 738, 1750, 1939, 5672, 6704, 20065, 11306, 20362, 36780, 53926, 77234, 116988, 146955, 219604, 353518, 479638, 643753, 1156116, 1393784, 1778612, 3767018, 3224712, 4227504, 6058692, 9406426, 13136745, 15425494, 19723654
Offset: 0

Views

Author

Seiichi Manyama, Oct 03 2017

Keywords

Crossrefs

Column k=5 of A293202.

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-> b(n$2):
    seq(a(n), n=0..50);  # Alois P. Heinz, Oct 04 2017

A293285 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of g.f. Product_{i>0} 1/(Sum_{j=0..k} j!*x^(j*i)).

Original entry on oeis.org

1, 1, 0, 1, -1, 0, 1, -1, 0, 0, 1, -1, -2, -1, 0, 1, -1, -2, 3, 1, 0, 1, -1, -2, -3, -1, -1, 0, 1, -1, -2, -3, 11, -5, 1, 0, 1, -1, -2, -3, -13, 7, 9, -1, 0, 1, -1, -2, -3, -13, 55, -15, 3, 2, 0, 1, -1, -2, -3, -13, -65, 33, -63, -20, -2, 0, 1, -1, -2, -3, -13, -65
Offset: 0

Views

Author

Seiichi Manyama, Oct 04 2017

Keywords

Examples

			Square array begins:
   1,  1,  1,  1,   1, ...
   0, -1, -1, -1,  -1, ...
   0,  0, -2, -2,  -2, ...
   0, -1,  3, -3,  -3, ...
   0,  1, -1, 11, -13, ...
   0, -1, -5,  7,  55, ...
		

Crossrefs

Columns k=0..2 give A000007, A081362, A293287.
Rows n=0..1 give A000012, (-1)*A057427.
Main diagonal gives A293251.
Showing 1-6 of 6 results.