A079069 - OEIS

%I #10 Jan 28 2017 16:24:55

%S 1,1,1,2,2,3,6,8,21,54,176,1155,9558,203456,11040645,1944642006,

%T 2246285672576,21470102051374515,4368221476369196469462,

%U 48227982626747161978326473216,93786160880652497618461924784373935445

%N a(n) = a(n-2) * a(n-3) + a(n-3), n>3. a(1) = a(2) = a(3) = 1.

%p 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

%t 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 *)

%o (PARI) {a(n) = if( n<4, n>0, (1 + a(n-2)) * a(n-3))}

%Y Cf. A078919.

%K nonn,easy

%O 1,4

%A _Michael Somos_, Dec 22 2002