A225221 Number of lattice paths without interior points from {4}^n to {0}^n using steps that decrement one component by 1.

1, 0, 2, 2550, 8059800, 57010275000, 801652441590000, 20393765925943410000, 872251852597491366000000, 59194435154364480600630000000, 6083868079208428011546743700000000, 911478727065442542708032537906700000000, 192819174440695429545254134608441231600000000

Offset

0,3

Comments

An interior point p = (p_1, ..., p_n) has n>0 components with 0<p_i<4 for 1<=i<=n.

Links

Alois P. Heinz, Table of n, a(n) for n = 0..45

Maple

b:= proc(n, l) option remember; local m; m:= nops(l);
      `if`(m=0 or l[m]=0, 1, `if`(l[1]>0 and l[m]<n, 0,
       add(`if`(l[i]=0, 0, b(n, sort(subsop(i=l[i]-1, l)))), i=1..m)))
    end:
a:= n-> b(4, [4$n]):
seq(a(n), n=0..12);

Crossrefs

Row n=4 of A225094.

Sequence in context: A199948 A261382 A281692 * A347654 A324426 A114067

Adjacent sequences: A225218 A225219 A225220 * A225222 A225223 A225224

Keyword

nonn

Author

Alois P. Heinz, May 02 2013

Status

approved