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A241594
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a(n) = -(8*a(n-4)*a(n-1)+57*a(n-3)*a(n-2))/a(n-5) with initial values 1, 0, -1, 1, 8, 57, -455.
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2
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1, 0, -1, 1, 8, 57, -455, 22352, 47767, 69739671, 3385862936, 1747973613295, -632038062613231, 319807929289790304, 778756000716629557903, 186509371006506937278833, -7581885296067966478838810840, -17592286469464275110206466526327, 594744699237794019378328459208828297
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OFFSET
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0,5
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LINKS
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G. C. Greubel, Table of n, a(n) for n = 0..90
R. W. Gosper and Richard C. Schroeppel, Somos Sequence Near-Addition Formulas and Modular Theta Functions, arXiv:math/0703470 [math.NT], 2007. See h_n.
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MAPLE
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f:=proc(n) option remember;
if n <= 2 then 1-n
elif n=3 then 1
elif n=4 then 8
elif n=5 then 57
elif n=6 then -455
else -(8*f(n-4)*f(n-1)+57*f(n-3)*f(n-2))/f(n-5); fi; end;
[seq(f(n), n=0..30)];
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MATHEMATICA
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a[n_] := a[n] = If[n <= 6, {1, 0, -1, 1, 8, 57, -455}[[n + 1]], -(8*a[n - 4]*a[n - 1] + 57*a[n - 3]*a[n - 2])/a[n - 5]];
Table[a[n], {n, 0, 18}] (* Jean-François Alcover, Dec 02 2017 *)
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PROG
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(Magma) I:=[22352, 47767, 69739671, 3385862936, 1747973613295]; [1, 0, -1, 1, 8, 57, -455] cat [n le 5 select I[n] else -(8*Self(n-4)*Self(n-1) + 57*Self(n-3)*Self(n-2))/Self(n-5): n in [1..20]]; // G. C. Greubel, Aug 08 2018
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CROSSREFS
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See A241595 for another version.
Sequence in context: A307642 A338676 A199555 * A241595 A208596 A324205
Adjacent sequences: A241591 A241592 A241593 * A241595 A241596 A241597
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KEYWORD
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sign
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AUTHOR
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N. J. A. Sloane, May 18 2014
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STATUS
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approved
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