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A276271 a(0) = a(1) = a(2) = a(3) = 1; for n > 3, a(n) = (a(n-1)^2+a(n-2)^2+a(n-3)^2+a(n-1)+a(n-2)+a(n-3))/a(n-4). 2
1, 1, 1, 1, 6, 46, 2206, 4870846, 3954191749561, 339905052007042640998641, 52373274877565894156748130733610185904753361, 563138297002425210235477817802336090254190075906443582099838858026136728896536841 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..15

FORMULA

a(n) = 8*a(n-1)*a(n-2)*a(n-3)-a(n-4)-1.

a(n) ~ 2^(-3/2) * c^(d^n), where c = 1.2578918597... and d = A058265 = 1.83928675521416... = (1 + (19 + 3*sqrt(33))^(1/3) + (19 - 3*sqrt(33))^(1/3))/3. - Vaclav Kotesovec, Mar 20 2017

MATHEMATICA

nxt[{a_, b_, c_, d_}]:={b, c, d, (b^2+c^2+d^2+b+c+d)/a}; NestList[nxt, {1, 1, 1, 1}, 12][[All, 1]] (* Harvey P. Dale, Mar 10 2017 *)

PROG

(Ruby)

def A(m, n)

  a = Array.new(m, 1)

  ary = [1]

  while ary.size < n + 1

    i = a[1..-1].inject(0){|s, i| s + i * i} + a[1..-1].inject(:+)

    break if i % a[0] > 0

    a = *a[1..-1], i / a[0]

    ary << a[0]

  end

  ary

end

def A276271(n)

  A(4, n)

end

CROSSREFS

Cf. A101879, A276122.

Sequence in context: A094655 A327364 A015865 * A145506 A256160 A184725

Adjacent sequences:  A276268 A276269 A276270 * A276272 A276273 A276274

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Aug 26 2016

STATUS

approved

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Last modified April 10 02:39 EDT 2020. Contains 333392 sequences. (Running on oeis4.)