cp's OEIS Frontend

A276284 a(0) = a(1) = a(2) = a(3) = a(4) = 1; for n > 4, a(n) = ( a(n-1)+a(n-3)+1 )*( a(n-2)+a(n-4)+1 ) / a(n-5).

%I A276284 #33 Dec 14 2021 16:54:01
%S A276284 1,1,1,1,1,9,33,385,13825,5474305,8430415841,1398605982547209,
%T A276284 30625582893143965429313,3098236789946633955987434183345281,
%U A276284 17332850039068891068793031113694107707268123637761
%N A276284 a(0) = a(1) = a(2) = a(3) = a(4) = 1; for n > 4, a(n) = ( a(n-1)+a(n-3)+1 )*( a(n-2)+a(n-4)+1 ) / a(n-5).
%H A276284 Seiichi Manyama, <a href="/A276284/b276284.txt">Table of n, a(n) for n = 0..21</a>
%F A276284 a(n) = (8-4*(-1)^n)*a(n-1)*a(n-3) - a(n-2) - a(n-4) - 1 for n>3.
%t A276284 RecurrenceTable[{a[n] == (a[n - 1] + a[n - 3] + 1) (a[n - 2] + a[n - 4] + 1)/a[n - 5], a[0] == a[1] == a[2] == a[3] == a[4] == 1}, a, {n, 0, 14}] (* _Michael De Vlieger_, Aug 27 2016 *)
%t A276284 nxt[{a_,b_,c_,d_,e_}]:={b,c,d,e,(e+c+1) (d+b+1)/a}; NestList[nxt,{1,1,1,1,1},15][[All,1]] (* _Harvey P. Dale_, Dec 14 2021 *)
%o A276284 (Ruby)
%o A276284 def A(m, n)
%o A276284   a = Array.new(2 * m + 1, 1)
%o A276284   ary = [1]
%o A276284   while ary.size < n + 1
%o A276284     i = (1..m).inject(1){|s, i| s + a[2 * i - 1]} * (1..m).inject(1){|s, i| s + a[2 * i]}
%o A276284     break if i % a[0] > 0
%o A276284     a = *a[1..-1], i / a[0]
%o A276284     ary << a[0]
%o A276284   end
%o A276284   ary
%o A276284 end
%o A276284 def A276284(n)
%o A276284   A(2, n)
%o A276284 end
%Y A276284 Cf. A276123.
%K A276284 nonn
%O A276284 0,6
%A A276284 _Seiichi Manyama_, Aug 27 2016