OFFSET
1,4
MAPLE
a:=proc(n) option remember; if n=1 then 1 elif n=2 then 1 elif n=3 then 1 else a(n-2)*a(n-3)+a(n-3); fi; end: seq(a(n), n=1..25); # Wesley Ivan Hurt, Jan 27 2017
MATHEMATICA
RecurrenceTable[{a[1]==a[2]==a[3]==1, a[n]==a[n-2]a[n-3]+a[n-3]}, a, {n, 25}] (* Harvey P. Dale, Jul 18 2015 *)
PROG
(PARI) {a(n) = if( n<4, n>0, (1 + a(n-2)) * a(n-3))}
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Michael Somos, Dec 22 2002
STATUS
approved