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A133471
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a(n) = (n^2)*a(n-1) + a(n-2).
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1
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0, 1, 4, 37, 596, 14937, 538328, 26393009, 1689690904, 136891356233, 13690825314204, 1656726754374917, 238582343455302252, 40322072770700455505, 7903364845400744581232, 1778297412287938231232705, 455252040910557587940153712, 131569618120563430852935655473
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OFFSET
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0,3
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COMMENTS
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Alternates between even and odd.
After a(3) = 37, which is the next prime?
Next primes are a(9) = 136891356233, a(51) = 2.5... * 10^132, a(249) = 1.7... * 10^980. - Charles R Greathouse IV, Mar 13 2015
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LINKS
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MAPLE
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if n <= 1 then
n;
else
n^2*procname(n-1)+procname(n-2) ;
end if;
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MATHEMATICA
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RecurrenceTable[{a[0]==0, a[1]==1, a[n]==n^2 a[n-1]+a[n-2]}, a, {n, 30}] (* or *) Module[{nn=20, frac}, frac=Range[nn]^2; Join[{0}, Table[Denominator[ FromContinuedFraction[Take[frac, n]]], {n, nn}]]] (* Harvey P. Dale, Mar 14 2015 *)
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PROG
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(PARI) v=vector(100); v[1]=1; v[2]=4; for(n=3, #v, v[n]=n^2*v[n-1]+v[n-2]); v=concat(0, v) \\ Charles R Greathouse IV, Mar 13 2015
(GAP) a:=[0, 1];; for n in [3..20] do a[n]:=(n-1)^2*a[n-1]+a[n-2]; od; a; # Muniru A Asiru, Oct 07 2018
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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