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A111236 a(1)=a(2)=a(3)=a(4)=1. For n >= 5, a(n)= (a(n-1)+a(n-2)) * (a(n-3)+a(n-4)). 0

%I

%S 1,1,1,1,4,10,28,190,3052,123196,27522064,89625932920,

%T 11318569384820032,312907271203608153807520,

%U 28053218967767813941001154374119168,317524819653692484884273872549799784105586335582976

%N a(1)=a(2)=a(3)=a(4)=1. For n >= 5, a(n)= (a(n-1)+a(n-2)) * (a(n-3)+a(n-4)).

%t RecurrenceTable[{a[1]==a[2]==a[3]==a[4]==1,a[n]==(a[n-1]+a[n-2]) (a[n-3]+ a[n-4])},a[n],{n,20}](* _Harvey P. Dale_, Aug 08 2011 *)

%o (PARI) a(n)=if(n<5,1,(a(n-1)+a(n-2)) *(a(n-3)+a(n-4))) (Klasen)

%K easy,nonn

%O 1,5

%A _Leroy Quet_, Oct 28 2005

%E More terms from Lambert Klasen (lambert.klasen(AT)gmx.net), Oct 31 2005

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Last modified September 21 05:55 EDT 2020. Contains 337267 sequences. (Running on oeis4.)