A263159 Number A(n,k) of lattice paths starting at {n}^k and ending when k or any component equals 0, using steps that decrement one or more components by one; square array A(n,k), n>=0, k>=0, read by antidiagonals.

1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 7, 13, 1, 1, 1, 15, 157, 63, 1, 1, 1, 31, 2101, 5419, 321, 1, 1, 1, 63, 32461, 717795, 220561, 1683, 1, 1, 1, 127, 580693, 142090291, 328504401, 9763807, 8989, 1, 1, 1, 255, 11917837, 39991899123, 944362553521, 172924236255, 454635973, 48639, 1, 1

Offset: 0

Author

Alois P. Heinz, Oct 11 2015

Keywords

• nonn
• tabl

Examples

			Square array A(n,k) begins:
  1, 1,    1,       1,            1,                1, ...
  1, 1,    3,       7,           15,               31, ...
  1, 1,   13,     157,         2101,            32461, ...
  1, 1,   63,    5419,       717795,        142090291, ...
  1, 1,  321,  220561,    328504401,     944362553521, ...
  1, 1, 1683, 9763807, 172924236255, 7622403922836151, ...
		

Links

• Alois P. Heinz, Antidiagonals n = 0..20, flattened

Crossrefs

Columns k=0+1, 2-10 give: A000012, A001850, A115866, A263162, A263163, A263164, A263165, A263166, A263167, A263168.

Rows n=0-1 give: A000012, A255047.

Main diagonal gives A263160.

Cf. A210472, A225094, A227578, A227655, A229142, A229345, A262809.

Programs

Maple

s:= proc(n) option remember; `if`(n=0, {[]},
      map(x-> [[x[], 0], [x[], 1]][], s(n-1)))
    end:
b:= proc(l) option remember; `if`(l=[] or l[1]=0, 1,
       add((p-> `if`(p[1]<0, 0, `if`(p[1]=0, 1, b(p)))
       )(sort(l-x)), x=s(nops(l)) minus {[0$nops(l)]}))
    end:
A:= (n, k)-> b([n$k]):
seq(seq(A(n,d-n), n=0..d), d=0..10);

Mathematica

g[k_] := Table[Reverse[IntegerDigits[n, 2]][[;;k]], {n, 2^k+1, 2^(k+1)-1}];
b[l_] := b[l] = If[l[[1]] == 0, 1, Sum[b[Sort[l - h]], {h, g[k]}]];
a[n_, k_] := If[n == 0 || k == 0 || k == 1, 1, b[Table[n, {k}]]];
Table[a[n-k, k], {n, 0, 10}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Apr 25 2020, after Alois P. Heinz in A115866 *)