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 A063404 a(0)=1; a(1)=1; a(2)=1; a(n) = a(n-1) + (1 + a(n-2))*(1 + a(n-3)). 1

%I #13 Jun 26 2018 04:56:54

%S 1,1,1,5,9,21,81,301,2105,26869,662881,57251101,17868890441,

%T 37968593886405,1023051637915653489,678457667444617722784941,

%U 38843832843299593293720040241881,694097227974493731990570304927658701989461

%N a(0)=1; a(1)=1; a(2)=1; a(n) = a(n-1) + (1 + a(n-2))*(1 + a(n-3)).

%H Harry J. Smith, <a href="/A063404/b063404.txt">Table of n, a(n) for n = 0..28</a>

%t RecurrenceTable[{a[0]==a[1]==a[2]==1,a[n]==a[n-1]+(1+a[n-2])(1+ a[n-3])}, a,{n,20}] (* _Harvey P. Dale_, Feb 27 2012 *)

%o (PARI) { a=a3=a2=a1=1; for (n = 0, 28, if (n>2, a=a1 + (1 + a2)*(1 + a3); a3=a2; a2=a1; a1=a); write("b063404.txt", n, " ", a) ) } \\ _Harry J. Smith_, Aug 20 2009

%K nonn,easy

%O 0,4

%A _Olivier GĂ©rard_, Jul 16 2001

%E One additional term from _Harvey P. Dale_, Feb 27 2012

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Last modified July 23 04:43 EDT 2024. Contains 374544 sequences. (Running on oeis4.)