A225220 Number of lattice paths without interior points from {n}^4 to {0}^4 using steps that decrement one component by 1.

1, 24, 1944, 132000, 8059800, 471369024, 27141228576, 1557898303104, 89658680843160, 5186780199744000, 301901643282754944, 17682835350047107968, 1041936263500353390624, 61736371470508652400000, 3676501723843796568912000, 219941299213693627194432000

Offset

0,2

Comments

An interior point p = (p_1, ..., p_4) has 4 components with 0<p_i<n for 1<=i<=4.

Links

Alois P. Heinz, Table of n, a(n) for n = 0..100

Maple

b:= proc(n, l) b(n, l):= `if`(l[4]=0, 1, `if`(l[1]>0 and l[4]<n, 0,
       add(`if`(l[i]=0, 0, b(n, sort(subsop(i=l[i]-1, l)))), i=1..4)))
    end:
a:= n-> b(n, [n$4]):
seq(a(n), n=0..20);

Crossrefs

Column k=4 of A225094.

Sequence in context: A006685 A002671 A328126 * A262010 A267075 A263605

Adjacent sequences: A225217 A225218 A225219 * A225221 A225222 A225223

Keyword

nonn

Author

Alois P. Heinz, May 02 2013

Status

approved