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A276268 a(0) = a(1) = a(2) = a(3) = 1; for n>3, a(n) = ( a(n-1)*a(n-2)*a(n-3) + 1 )^2 / a(n-4). 1
1, 1, 1, 1, 4, 25, 10201, 1040606050201, 17606710134796383100801078407630169, 1397251576763829044923817239566095383950667477080314561212188721224520791793149263311589905001958916 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..11

FORMULA

a(n) = A276267(n)^2.

MATHEMATICA

RecurrenceTable[{a[n] == (a[n - 1] a[n - 2] a[n - 3] + 1)^2/a[n - 4], a[0] == a[1] == a[2] == a[3] == 1}, a, {n, 0, 10}] (* Michael De Vlieger, Aug 26 2016 *)

PROG

(Ruby)

def A(m, n)

  a = Array.new(m, 1)

  ary = [1]

  while ary.size < n + 1

    i = a[1..-1].inject(:*) + 1

    i *= i

    break if i % a[0] > 0

    a = *a[1..-1], i / a[0]

    ary << a[0]

  end

  ary

end

def A276268(n)

  A(4, n)

end

CROSSREFS

Cf. A081068, A276266, A276267.

Sequence in context: A284106 A063802 A276266 * A086909 A046963 A022386

Adjacent sequences:  A276265 A276266 A276267 * A276269 A276270 A276271

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Aug 26 2016

STATUS

approved

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Last modified May 22 06:32 EDT 2019. Contains 323478 sequences. (Running on oeis4.)