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A068200
One of a family of sequences that interpolates between the Bell numbers and the factorials.
3
1, 2, 6, 24, 120, 696, 4536, 32568, 254136, 2133816, 19130040, 182000952, 1828296888, 19311334200, 213709376184, 2470302259512, 29746381049016, 372270346391352, 4831940144914104, 64925998174811448, 901626111996723384, 12920858504042924856
OFFSET
0,2
REFERENCES
G. Labelle et al., Stirling numbers interpolation using permutations with forbidden subsequences, Discrete Math. 246 (2002), 177-195.
MAPLE
g:= proc(n) option remember; `if` (n=0, 1, (1+add(binomial (n-1, k-1) * g(n-k), k=1..n-1)) * 4) end:
a:= n-> `if`(n<=1, n+1, 6*g(n-2)): seq (a(n), n=0..25); # Sean A. Irvine, Feb 02 2024
CROSSREFS
Cf. A000110, A001861, A068199, this, A068201, ..., A000142.
Sequence in context: A214611 A177528 A177527 * A189847 A189284 A274970
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 23 2002
EXTENSIONS
More terms from Sean A. Irvine, Feb 02 2024
STATUS
approved