OFFSET
1,5
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..25
MATHEMATICA
{1, 1, 1}~Join~NestList[{#2, #3, #4, #4 #2 + #3 #1} & @@ # &, {1, 1, 1, 1}, 14][[All, -1]] (* Michael De Vlieger, Sep 28 2017 *)
PROG
(PARI) a(n)=if(n<5, 1, a(n-1)*a(n-3) + a(n-2)*a(n-4)) \\ Lambert Klasen
(Magma) I:=[1, 1, 1, 1, 2]; [n le 4 select I[n] else Self(n-1)*Self(n-3)+Self(n-2)*Self(n-4) : n in [1..20]]; // Vincenzo Librandi, Sep 29 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Leroy Quet, Nov 01 2005
EXTENSIONS
More terms from Lambert Klasen (lambert.klasen(AT)gmx.net), Nov 06 2005
STATUS
approved