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A276259 a(n) = 5*a(n-1)*a(n-2)*a(n-3) - a(n-4) with n>4, a(1) = a(2) = a(3) = a(4) = 1. 3
1, 1, 1, 1, 4, 19, 379, 144019, 5185404091, 1415179768826376436, 5284257989697826589787882104688841, 193886796198316302609610159795591363955441027433554915785933561 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..16

FORMULA

a(1)=a(2)=a(3)=a(4)=1; for n>4, a(n) = (a(n-1)^2 + a(n-2)^2 + a(n-3)^2 + 1) / a(n-4).

a(n)*a(n+1)*a(n+2)*a(n+3) = (a(n)^2 + a(n+1)^2 + a(n+2)^2 + a(n+3)^2 + 1)/5.

MATHEMATICA

RecurrenceTable[{a[n] == 5 a[n - 1] a[n - 2] a[n - 3] - a[n - 4], a[1] == a[2] == a[3] == a[4] == 1}, a, {n, 12}] (* Michael De Vlieger, Aug 26 2016 *)

PROG

(Ruby)

def A(m, n)

  a = Array.new(m, 1)

  ary = [1]

  while ary.size < n

    a = *a[1..-1], *a[1..-1].inject(:*) * (m + 1) - a[0]

    ary << a[0]

  end

  ary

end

def A276259(n)

  A(4, n)

end

CROSSREFS

Cf. A001519, A276258.

Sequence in context: A292167 A126147 A007411 * A072879 A112958 A080991

Adjacent sequences:  A276256 A276257 A276258 * A276260 A276261 A276262

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Aug 26 2016

STATUS

approved

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Last modified January 17 12:18 EST 2020. Contains 330958 sequences. (Running on oeis4.)