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A141522
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a(1) = 0, a(2) = a(3) = 1; a(n) = a(n-1)*a(n-2) + a(n-1)*a(n-3) for n > 3.
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1
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0, 1, 1, 1, 2, 4, 12, 72, 1152, 96768, 118444032, 11598039613440, 1374840894208868352000, 15945621994910596019667697926144000, 21922693387137438627357958684974264478793362424463360000
(list;
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listen;
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OFFSET
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1,5
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REFERENCES
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Martin Gardner, Mathematical Circus, Random House, New York, 1981, p. 165.
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LINKS
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MATHEMATICA
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Nest[Append[#, #[[-1]] #[[-2]] + #[[-1]] #[[-3]]] &, {0, 1, 1}, 12] (* Michael De Vlieger, Dec 17 2017 *)
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PROG
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(MATLAB)
function y=fib(n)
%Generates running geometric numbers( second kind)
fz(1)=0; fz(2)=1; fz(3)=1;
for k=4:n
fz(k)=fz(k-1)*(fz(k-2)+fz(k-3));
end
y=fz(n);
(PARI) /* script that avoids arrays */
geom(n) = {
local(a=0, b=1, c=1, d);
print1(a", "b", "c", ");
for(x=1, n-3,
d=(a+b)*c;
print1(d", ");
a=b; b=c; c=d;
)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Matt Wynne (matwyn(AT)verizon.net), Aug 11 2008
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STATUS
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approved
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