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 1-3 of 3 results.

A151511 The triangle in A151359 read by rows downwards.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 3, 1, 0, 1, 7, 6, 1, 0, 1, 15, 25, 10, 1, 0, 1, 31, 90, 65, 15, 1, 0, 0, 63, 301, 350, 140, 21, 1, 0, 0, 119, 966, 1701, 1050, 266, 28, 1, 0, 0, 210, 2989, 7770, 6951, 2646, 462, 36, 1, 0, 0, 336, 8925, 33985, 42525, 22827, 5880, 750, 45, 1, 0, 0, 462, 25641
Offset: 0

Views

Author

N. J. A. Sloane, May 14 2009

Keywords

Comments

The Bell transform of g(n) = 1 if n<6 else 0. For the definition of the Bell transform see A264428. - Peter Luschny, Jan 19 2016

Examples

			Triangle begins:
1
0 1
0 1 1
0 1 3 1
0 1 7 6 1
0 1 15 25 10 1
0 1 31 90 65 15 1
0 0 63 301 350 140 21 1
0 0 119 966 1701 1050 266 28 1

Links

Crossrefs

Begins in same way as triangle of Stirling numbers of second kind, A048993, but is strictly different. N. J. A. Sloane, Aug 09 2017
Cf. A148092 (row sums), A122848, A111246, A144644, A151509.

Programs

  • Mathematica
    Unprotect[Power]; 0^0 = 1; a[n_ /; 1 <= n <= 6] = 1; a[] = 0; T[n, k_] := T[n, k] = If[k == 0, a[0]^n, Sum[Binomial[n - 1, j - 1] a[j] T[n - j, k - 1], {j, 0, n - k + 1}]]; Table[T[n, k], {n, 0, 9}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jan 20 2016, after Peter Luschny *)
  • Sage
    # uses[bell_matrix from A264428]
bell_matrix(lambda n: 1 if n<6 else 0, 12) # Peter Luschny, Jan 19 2016

Formula

Bivariate e.g.f. A151511(x,t) = Sum_{n>=0, k>=0} T(n,k)*x^n*t^k/n! = exp(t*G6(x)), where G6(x) = Sum_{i=1..6} x^i/i! is the e.g.f. of column 1. - R. J. Mathar, May 28 2019

Extensions

Row 9 added by Michel Marcus, Feb 13 2014
More rows from R. J. Mathar, May 28 2019

A151512 The triangle in A151359 read by rows upwards.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 3, 1, 0, 1, 6, 7, 1, 0, 1, 10, 25, 15, 1, 0, 1, 15, 65, 90, 31, 1, 0, 1, 21, 140, 350, 301, 63, 0, 0, 1, 28, 266, 1050, 1701, 966, 119, 0, 0, 1, 36, 462, 2646, 6951, 7770, 2989, 210, 0, 0, 1, 45, 750, 5880, 22827, 42525, 33985, 8925, 336, 0, 0
Offset: 0

Views

Author

N. J. A. Sloane, May 14 2009

Keywords

Comments

Conjectured: The i-th element of row j is the number of different equivalence relationships, within a set of (j-1) element, having (j-i) equivalence classes. For example: row 5 = [1, 6, 7, 1, 0] means that, in a set of 4 elements, there exists 7 equivalence relationships having 3 different equivalence classes. - Philippe Beaudoin, Nov 09 2013

Examples

			Triangle begins:
  1
  1  0
  1  1   0
  1  3   1    0
  1  6   7    1    0
  1 10  25   15    1   0
  1 15  65   90   31   1   0
  1 21 140  350  301  63   0 0
  1 28 266 1050 1701 966 119 0 0

Links

Crossrefs

Cf. A148092 (row sums), A151511 (row-reversed).

Programs

  • Mathematica
    Unprotect[Power]; 0^0 = 1; a[n_ /; 1 <= n <= 6] = 1; a[] = 0; t[n, k_] := t[n, k] = If[k == 0, a[0]^n, Sum[Binomial[n - 1, j - 1] a[j] t[n - j, k - 1], {j, 0, n - k + 1}]]; Table[Table[t[n - 1, k], {k, n - 1, 0, -1}], {n, 0, 10}] // Flatten (* Jean-François Alcover, Jan 20 2016, using Peter Luschny's Bell transform *)

Extensions

Row 9 added by Michel Marcus, Feb 13 2014
Row 10 from R. J. Mathar, May 28 2019

A151338 Triangle read by rows: T(n,k) = number of partitions of [1..k] into n nonempty clumps of sizes 1, 2, 3, 4 or 5 (n >= 0, 0 <= k <= 5n).

Original entry on oeis.org

1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 3, 7, 15, 31, 56, 91, 126, 126, 0, 0, 0, 1, 6, 25, 90, 301, 938, 2737, 7455, 18711, 41811, 81081, 126126, 126126, 0, 0, 0, 0, 1, 10, 65, 350, 1701, 7686, 32725, 132055, 505351, 1824823, 6173167, 19339320, 55096041
Offset: 0

Views

Author

N. J. A. Sloane, May 13 2009

Keywords

Comments

Row n has 5n+1 entries.

Examples

			The triangle begins:
1
0, 1, 1, 1, 1, 1
0, 0, 1, 3, 7, 15, 31, 56, 91, 126, 126
0, 0, 0, 1, 6, 25, 90, 301, 938, 2737, 7455, 18711, 41811, 81081, 126126, 126126
0, 0, 0, 0, 1, 10, 65, 350, 1701, 7686, 32725, 132055, 505351, 1824823, 6173167, 19339320, 55096041, 138654516, 295891596, 488864376, 488864376
0, 0, 0, 0, 0, 1, 15, 140, 1050, 6951, 42315, 241780, 1310925, 6782776, 33549516, 158533375, 713733020, 3046944901, 12246267033, 45892143297, 158167994985, 491492022021, 1336310771796, 3030225834636, 5194672859376, 5194672859376
...

Links

Crossrefs

This is one of a sequence of triangles: A144331, A144385, A144643, A151338, A151359, ...
See A151509, A151510 for other versions.
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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