login
A050149
a(n) = T(n,n-3), array T as in A050143.
1
1, 15, 80, 432, 2352, 12896, 71136, 394400, 2196128, 12273648, 68811184, 386838480, 2179890000, 12309739968, 69641542848, 394643939904, 2239678552640, 12727572969680, 72415319422992, 412470467298032
OFFSET
3,2
FORMULA
a(n) = Sum_{s=1..n} binomial(n,s)*binomial(s+n-5,n-4) = n*hypergeom([-n + 1, n-3], [2], -1) for n >= 4 and a(1) = 1. - Petros Hadjicostas, Feb 14 2021
CROSSREFS
Sequence in context: A370533 A123865 A024002 * A055815 A370535 A338414
KEYWORD
nonn
STATUS
approved