A374649 a(n) = n! - 2(n-1)! + 3(n-2)!.

3, 5, 18, 90, 552, 3960, 32400, 297360, 3024000, 33747840, 410054400, 5388768000, 76161254400, 1151998848000, 18568976025600, 317764871424000, 5753767219200000, 109907415281664000, 2208818928476160000, 46590073456582656000, 1029117549458718720000

Offset

2,1

Links

Table of n, a(n) for n=2..22.

Formula

D-finite with recurrence a(n) +(-n-2)*a(n-1) +(2*n-1)*a(n-2) +3*(-n+4)*a(n-3)=0. - R. J. Mathar, Jul 30 2024

Maple

A374649 := proc(n)
    n!-2*(n-1)!+3*(n-2)! ;
end proc:
seq(A374649(n), n=2..50) ; # R. J. Mathar, Jul 30 2024

Mathematica

Table[n! - 2 (n - 1)! + 3 (n - 2)!, {n, 2, 25}]

Crossrefs

Cf. A000142, A374650.

Sequence in context: A303684 A022489 A176749 * A374917 A145774 A348778

Adjacent sequences: A374646 A374647 A374648 * A374650 A374651 A374652

Keyword

nonn

Author

Clark Kimberling, Jul 25 2024

Status

approved