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 A276097 A nonlinear recurrence of order 5: a(1)=a(2)=a(3)=a(4)=a(5)=1; a(n)=(a(n-1)+a(n-2)+a(n-3)+a(n-4))^2/a(n-5). 3
 1, 1, 1, 1, 1, 16, 361, 143641, 20741472361, 430214650013601071641, 11567790319010747187536221088708755344001, 370675271093071368960746074163948008803845834307486807769098691609909105887376 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 COMMENTS All terms are perfect squares. LINKS Seiichi Manyama, Table of n, a(n) for n = 1..15 FORMULA a(n) = A072879(n)^2. a(n) = 25*a(n-1)*a(n-2)*a(n-3)*a(n-4) - 2a(n-1) - 2a(n-2) - 2a(n-3) - 2a(n-4) - a(n-5). a(n)*a(n-1)*a(n-2)*a(n-3)*a(n-4) = ((a(n) + a(n-1) + a(n-2) + a(n-3) + a(n-4))/5)^2. MATHEMATICA RecurrenceTable[{a[1] == a[2] == a[3] == a[4] == a[5] == 1, a[n] == (a[n-1] + a[n-2] + a[n-3] + a[n-4])^2 / a[n-5]}, a, {n, 15}] (* Vincenzo Librandi, Aug 21 2016 *) PROG (Ruby) def A(m, n)   a = Array.new(m, 1)   ary = [1]   while ary.size < n     i = a[1..-1].inject(:+)     j = i * i     break if j % a[0] > 0     a = *a[1..-1], j / a[0]     ary << a[0]   end   ary end def A276097(n)   A(5, n) end CROSSREFS Cf. A072879, A072882, A276095. Sequence in context: A000488 A025759 A276257 * A265476 A008427 A187177 Adjacent sequences:  A276094 A276095 A276096 * A276098 A276099 A276100 KEYWORD nonn AUTHOR Seiichi Manyama, Aug 18 2016 STATUS approved

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Last modified July 27 06:56 EDT 2021. Contains 346304 sequences. (Running on oeis4.)