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A225220 Number of lattice paths without interior points from {n}^4 to {0}^4 using steps that decrement one component by 1. 2
1, 24, 1944, 132000, 8059800, 471369024, 27141228576, 1557898303104, 89658680843160, 5186780199744000, 301901643282754944, 17682835350047107968, 1041936263500353390624, 61736371470508652400000, 3676501723843796568912000, 219941299213693627194432000 (list; graph; refs; listen; history; text; internal format)
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: A003738 A006685 A002671 * A262010 A267075 A263605

Adjacent sequences:  A225217 A225218 A225219 * A225221 A225222 A225223

KEYWORD

nonn

AUTHOR

Alois P. Heinz, May 02 2013

STATUS

approved

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Last modified August 22 20:47 EDT 2019. Contains 326209 sequences. (Running on oeis4.)