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.

A084249 Triangle T(n,k) read by rows: permutations on 123...n with one abc pattern and no aj pattern with j<=k, n>2, k

Original entry on oeis.org

1, 6, 2, 27, 12, 3, 110, 55, 19, 4, 429, 229, 91, 27, 5, 1638, 912, 393, 136, 36, 6, 6188, 3549, 1614, 612, 191, 46, 7, 23256, 13636, 6447, 2601, 897, 257, 57, 8, 87210, 52020, 25332, 10695, 3951, 1260, 335, 69, 9, 326876, 197676, 98532
Offset: 3

Views

Author

Ralf Stephan, May 21 2003

Keywords

Comments

See A228708 for further information.

Examples

			Full triangle begins:
0
0,0
0,0,0
1,1,0,0
6,6,2,0,0
27,27,12,3,0,0
110,110,55,19,4,0,0
429,429,229,91,27,5,0,0
1638,1638,912,393,136,36,6,0,0
6188,6188,3549,1614,612,191,46,7,0,0
23256,23256,13636,6447,2601,897,257,57,8,0,0
...
		

Crossrefs

See A228708 for the full triangle.
T(n, 1) = A003517(n+1). Cf. A001089.

Programs

  • PARI
    for(n=1,15, for(k=1,n-2,print1(binomial(2*n-k-1,n)-binomial(2*n-k-1,n+3)+binomial(2*n-2*k-2,n-k-4)-binomial(2*n-2*k-2,n-k-1)+binomial(2*n-2*k-3,n-k-4)-binomial(2*n-2*k-3,n-k-2)",")))

Formula

T(n, k) = C(2n-k-1, n) - C(2n-k-1, n+3) + C(2n-2k-2, n-k-4) - C(2n-2k-2, n-k-1) + C(2n-2k-3, n-k-4) - C(2n-2k-3, n-k-2).
T(n, n-2) = n-2, T(n, k) = T(n, k+1) + T(n-1, k-1) + T(n-k, 2).

A229158 Triangle T(n,k) read by rows: T(n,k) = number of permutations on 123...n with exactly two abc patterns and no aj pattern with j<=k, for n>=0, 0<=k<=n.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 3, 1, 0, 0, 24, 24, 12, 2, 0, 0, 133, 133, 74, 23, 3, 0, 0, 635, 635, 371, 141, 36, 4, 0, 0, 2807, 2807, 1688, 709, 227, 51, 5, 0, 0, 11864, 11864, 7276, 3248, 1168, 334, 68, 6, 0, 0, 48756, 48756, 30340, 14121, 5459, 1771, 464, 87, 7, 0, 0
Offset: 0

Views

Author

N. J. A. Sloane, Sep 15 2013

Keywords

Comments

See Noonan-Zeilberger for precise definition.

Examples

			Triangle begins:
0,
0,0,
0,0,0,
0,0,0,0,
3,3,1,0,0,
24,24,12,2,0,0,
133,133,74,23,3,0,0,
635,635,371,141,36,4,0,0,
2807,2807,1688,709,227,51,5,0,0,
11864,11864,7276,3248,1168,334,68,6,0,0,
48756,48756,30340,14121,5459,1771,464,87,7,0,0
...
		

Crossrefs

A229160 Triangle T(n,k) read by rows: T(n,k) = number of permutations on 123...n with exactly one cab pattern and no aj pattern with j<=k, for n>=0, 0<=k<=n.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 5, 5, 2, 0, 0, 21, 21, 11, 3, 0, 0, 84, 84, 49, 19, 4, 0, 0, 330, 330, 204, 92, 29, 5, 0, 0, 1287, 1287, 825, 405, 153, 41, 6, 0, 0, 5005, 5005, 3289, 1705, 715, 235, 55, 7, 0, 0, 19448, 19448, 13013, 7007, 3146, 1166, 341, 71, 8, 0, 0
Offset: 0

Views

Author

N. J. A. Sloane, Sep 15 2013

Keywords

Comments

See Noonan-Zeilberger for precise definition.

Examples

			Triangle begins:
0,
0,0,
0,0,0,
1,1,0,0,
5,5,2,0,0,
21,21,11,3,0,0,
84,84,49,19,4,0,0,
330,330,204,92,29,5,0,0,
1287,1287,825,405,153,41,6,0,0,
5005,5005,3289,1705,715,235,55,7,0,0,
19448,19448,13013,7007,3146,1166,341,71,8,0,0,
...
		

Crossrefs

Showing 1-3 of 3 results.