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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). 1
1, 1, 1, 1, 1, 9, 33, 385, 13825, 5474305, 8430415841, 1398605982547209, 30625582893143965429313, 3098236789946633955987434183345281, 17332850039068891068793031113694107707268123637761 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..21

FORMULA

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

MATHEMATICA

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 *)

PROG

(Ruby)

def A(m, n)

  a = Array.new(2 * m + 1, 1)

  ary = [1]

  while ary.size < n + 1

    i = (1..m).inject(1){|s, i| s += a[2 * i - 1]} * (1..m).inject(1){|s, i| s += a[2 * i]}

    break if i % a[0] > 0

    a = *a[1..-1], i / a[0]

    ary << a[0]

  end

  ary

end

def A276284(n)

  A(2, n)

end

CROSSREFS

Cf. A276123.

Sequence in context: A183939 A145952 A172498 * A275695 A145925 A028568

Adjacent sequences:  A276281 A276282 A276283 * A276285 A276286 A276287

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Aug 27 2016

STATUS

approved

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Last modified October 23 19:34 EDT 2018. Contains 316530 sequences. (Running on oeis4.)