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.

Previous Showing 11-13 of 13 results.

A011967 4th differences of Bell numbers.

Original entry on oeis.org

4, 15, 67, 322, 1657, 9089, 52922, 325869, 2114719, 14418716, 103004851, 769052061, 5987339748, 48506099635, 408157244967, 3561086589202, 32164670915029, 300324194090773, 2894932531218482, 28773297907499129
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    Differences[BellB[Range[0, 50]], 4] (* Vladimir Joseph Stephan Orlovsky, May 25 2011 *)
  • Python
    # requires python 3.2 or higher. Otherwise use def'n of accumulate in python docs.
    from itertools import accumulate
    A011967_list, blist, b = [4], [5, 7, 10, 15], 15
    for _ in range(250):
        blist = list(accumulate([b]+blist))
        b = blist[-1]
        A011967_list.append(blist[-5]) # Chai Wah Wu, Sep 20 2014

A182930 Triangle read by rows: Number of set partitions of {1,2,..,n} such that |k| is a block and no block |m| with m < k exists, (1 <= n, 1 <= k <= n).

Original entry on oeis.org

1, 1, 0, 2, 1, 1, 5, 3, 2, 1, 15, 10, 7, 5, 4, 52, 37, 27, 20, 15, 11, 203, 151, 114, 87, 67, 52, 41, 877, 674, 523, 409, 322, 255, 203, 162, 4140, 3263, 2589, 2066, 1657, 1335, 1080, 877, 715, 21147, 17007, 13744, 11155, 9089, 7432, 6097, 5017, 4140, 3425
Offset: 1

Views

Author

Peter Luschny, Apr 08 2011

Keywords

Comments

Mirror image of A106436. - Alois P. Heinz, Jan 29 2019

Examples

			T(4,2) = card({2|134, 2|3|14, 2|4|13}) = 3.
[1]     1,
[2]     1,    0,
[3]     2,    1,    1,
[4]     5,    3,    2,    1,
[5]    15,   10,    7,    5,    4,
[6]    52,   37,   27,   20,   15,   11,
     [-1-] [-2-] [-3-] [-4-] [-5-] [-6-]
		

Crossrefs

T(2n+1,n+1) gives A020556.

Programs

  • Maple
    T := proc(n, k) option remember; if n = 1 then 1 elif n = k then T(n-1,1) - T(n-1,n-1) else T(n-1,k) + T(n, k+1) fi end:
    A182930 := (n,k) -> T(n,k); seq(print(seq(A182930(n,k),k=1..n)),n=1..6);
  • Mathematica
    T[n_, k_] := T[n, k] = Which[n == 1, 1, n == k, T[n-1, 1] - T[n-1, n-1], True, T[n-1, k] + T[n, k+1]];
    Table[T[n, k], {n, 1, 10}, {k, 1, n}] (* Jean-François Alcover, Jun 22 2019 *)

Formula

Recursion: The value of T(n,k) is, if n < 0 or k < 0 or k > n undefined, else if n = 1 then 1 else if k = n then T(n-1,1) - T(n-1,n-1); in all other cases T(n,k) = T(n,k+1) + T(n-1,k).

A191099 5th differences of Bell numbers.

Original entry on oeis.org

11, 52, 255, 1335, 7432, 43833, 272947, 1788850, 12303997, 88586135, 666047210, 5218287687, 42518759887, 359651145332, 3152929344235, 28603584325827, 268159523175744, 2594608337127709, 25878365376280647, 265770087291261082, 2807571511844891521
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    Differences[BellB[Range[0, 50]], 5]
Previous Showing 11-13 of 13 results.