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.

A303869 Triangle read by rows: T(n,k) = number of noncrossing path sets on n nodes up to rotation with k paths and isolated vertices allowed.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 3, 4, 2, 1, 4, 11, 8, 2, 1, 10, 34, 39, 16, 3, 1, 16, 92, 144, 90, 25, 3, 1, 36, 256, 545, 473, 197, 40, 4, 1, 64, 672, 1878, 2184, 1246, 370, 56, 4, 1, 136, 1762, 6296, 9436, 7130, 2910, 658, 80, 5, 1, 256, 4480, 20100, 38025, 36690, 19698, 6090, 1080, 105, 5, 1
Offset: 1

Views

Author

Andrew Howroyd, May 01 2018

Keywords

Examples

			Triangle begins:
    1;
    1,    1;
    1,    1,    1;
    3,    4,    2,    1;
    4,   11,    8,    2,    1;
   10,   34,   39,   16,    3,    1;
   16,   92,  144,   90,   25,    3,   1;
   36,  256,  545,  473,  197,   40,   4,  1;
   64,  672, 1878, 2184, 1246,  370,  56,  4, 1;
  136, 1762, 6296, 9436, 7130, 2910, 658, 80, 5, 1;
  ...
		

Crossrefs

Row sums are A303836.
Column 1 is A051437(n-3).

Programs

  • PARI
    \\ See A303732 for NCPathSetsModCyclic
    { my(rows=Vec(NCPathSetsModCyclic(vector(10, k, y))-1));
    for(n=1, #rows, for(k=1,n,print1(polcoeff(rows[n],k), ", ")); print;)}