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A184121 A (4,-3) Somos-4 sequence. 2
1, -1, -7, -31, -23, 2239, 39889, 603521, -27466831, -2445382081, -204734091383, 7545563759329, 7265319037194073, 2502938339020429439, 404477135616551491361, -932929530161758614571519 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
Hankel transform of A184120.
LINKS
FORMULA
a(n) = (4*a(n-1)*a(n-3) - 3*a(n-2)^2)/a(n-4).
MATHEMATICA
RecurrenceTable[{a[0]==1, a[1]==-1, a[2]==-7, a[3]==-31, a[n]==(4a[n-1] a[n-3]- 3a[n-2]^2)/a[n-4]}, a, {n, 20}] (* Harvey P. Dale, Apr 03 2016 *)
PROG
(Magma) I:=[-23, 2239, 39889, 603521]; [1, -1, -7, -31] cat [n le 4 select I[n] else (4*Self(n-1)*Self(n-3) - 3*Self(n-2)^2 )/Self(n-4): n in [1..30]]; // G. C. Greubel, Aug 14 2018
CROSSREFS
Sequence in context: A221402 A065916 A122654 * A167768 A103630 A205711
KEYWORD
sign,easy
AUTHOR
Paul Barry, Jan 09 2011
STATUS
approved

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Last modified April 23 20:27 EDT 2024. Contains 371916 sequences. (Running on oeis4.)