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.

A293202 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} j!*x^(j*i).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 3, 2, 0, 1, 1, 3, 2, 2, 0, 1, 1, 3, 8, 6, 3, 0, 1, 1, 3, 8, 6, 7, 4, 0, 1, 1, 3, 8, 30, 13, 12, 5, 0, 1, 1, 3, 8, 30, 13, 24, 13, 6, 0, 1, 1, 3, 8, 30, 133, 48, 37, 22, 8, 0, 1, 1, 3, 8, 30, 133, 48, 61, 46, 26, 10, 0, 1, 1, 3, 8, 30, 133, 768, 181, 142, 98, 42, 12, 0
Offset: 0

Views

Author

Seiichi Manyama, Oct 02 2017

Keywords

Examples

			Square array begins:
   1, 1, 1,  1,  1, ...
   0, 1, 1,  1,  1, ...
   0, 1, 3,  3,  3, ...
   0, 2, 2,  8,  8, ...
   0, 2, 6,  6, 30, ...
   0, 3, 7, 13, 13, ...
		

Crossrefs

Columns k=0..5 give A000007, A000009, A293204, A289485, A289486, A293250.
Rows n=0..1 give A000012, A057427.
Main diagonal gives A161779.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(b(n-i*j, i-1, k)*j!, j=0..min(k, n/i))))
        end:
    A:= (n, k)-> b(n$2, k):
    seq(seq(A(n, d-n), n=0..d), d=0..12);  # Alois P. Heinz, Oct 02 2017
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0, 1, If[i < 1, 0, Sum[b[n - i j, i - 1, k] j!, {j, 0, Min[k, n/i]}]]];
    A [n_, k_] := b[n, n, k];
    Table[Table[A[n, d-n], {n, 0, d}], {d, 0, 12}] // Flatten (* Jean-François Alcover, Dec 06 2019, after Alois P. Heinz *)

A290216 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=1..k} j*x^(j*i)).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 3, 2, 0, 1, 1, 3, 2, 2, 0, 1, 1, 3, 5, 6, 3, 0, 1, 1, 3, 5, 6, 7, 4, 0, 1, 1, 3, 5, 10, 10, 12, 5, 0, 1, 1, 3, 5, 10, 10, 18, 13, 6, 0, 1, 1, 3, 5, 10, 15, 22, 25, 22, 8, 0, 1, 1, 3, 5, 10, 15, 22, 29, 34, 26, 10, 0, 1, 1, 3, 5
Offset: 0

Views

Author

Seiichi Manyama, Oct 06 2017

Keywords

Examples

			Square array begins:
   1, 1, 1,  1,  1, ...
   0, 1, 1,  1,  1, ...
   0, 1, 3,  3,  3, ...
   0, 2, 2,  5,  5, ...
   0, 2, 6,  6, 10, ...
   0, 3, 7, 10, 10, ...
		

Crossrefs

Columns k=0..3 give A000007, A000009, A293204, A290269.
Rows n=0 gives A000012.
Main diagonal gives A077285.
Product_{i>0} (1 + Sum_{j=1..k} j*x^(j*i))^m: A290217 (m=-1), this sequence (m=1), A293377 (m=2).
Cf. A293305.

A293072 G.f.: Product_{m>0} (1-x^m+2!*x^(2*m)).

Original entry on oeis.org

1, -1, 1, 0, 0, -3, 4, -3, 4, -2, 0, -6, 9, -10, 10, -5, 10, -16, 20, -28, 22, -18, 19, -32, 54, -50, 45, -38, 44, -78, 106, -118, 96, -98, 110, -129, 192, -216, 204, -182, 213, -286, 368, -412, 366, -362, 394, -524, 676, -714, 680, -641, 742, -936, 1170
Offset: 0

Views

Author

Seiichi Manyama, Oct 03 2017

Keywords

Crossrefs

Column k=2 of A293071.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(b(n-i*j, i-1)*j!*(-1)^j, j=0..min(2, n/i))))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..60);  # Alois P. Heinz, Oct 04 2017
  • Mathematica
    nmax = 100; CoefficientList[Series[Product[1 - x^k + 2*x^(2*k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Oct 05 2017 *)
  • PARI
    Vec(prod(m=1, 80, 1-x^m+2*x^(2*m)) + O(x^80)) \\ Michel Marcus, Oct 04 2017

A293287 G.f.: Product_{m>0} 1/(1 + x^m + 2!*x^(2*m)).

Original entry on oeis.org

1, -1, -2, 3, -1, -5, 9, 3, -20, 16, 20, -54, 19, 89, -123, -56, 287, -181, -383, 748, 37, -1520, 1406, 1619, -4439, 1190, 7768, -10102, -5494, 25673, -14754, -36660, 66367, 7047, -139852, 125785, 153573, -405349, 98671, 712275, -909382, -514965, 2332540, -1303341
Offset: 0

Views

Author

Seiichi Manyama, Oct 04 2017

Keywords

Crossrefs

Column k=2 of A293285.
Cf. A293204.

Programs

  • PARI
    Vec(prod(m=1, 50, 1/(1 + x^m + 2!*x^(2*m))) + O(x^50)) \\ Michel Marcus, Oct 05 2017

Formula

Convolution inverse of A293204.

A293253 Expansion of Product_{k>=1} (1 + x^k + x^(k^2)).

Original entry on oeis.org

1, 2, 1, 3, 4, 6, 6, 8, 12, 15, 20, 22, 30, 35, 46, 53, 67, 80, 97, 117, 138, 165, 195, 231, 272, 323, 378, 442, 514, 600, 696, 806, 931, 1078, 1240, 1431, 1638, 1881, 2147, 2461, 2802, 3197, 3632, 4131, 4685, 5310, 6009, 6790, 7670, 8652, 9749, 10968, 12336
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 04 2017

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 100; CoefficientList[Series[Product[(1+x^k+x^(k^2)), {k, 1, nmax}], {x, 0, nmax}], x]
Showing 1-5 of 5 results.