login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A188315 A (25,-29) Somos-4 sequence. 2
1, 1, -4, -129, -3689, -113689, 7001471, 7911171596, 6480598259201, 5987117709349201, -4830209396684261199, -230318343950087449971199, -5423908604123397486016003604, -147547506573676549005535542233729, 739578212227710098047348234126634311 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
Hankel transform of A188314.
LINKS
FORMULA
a(n) = (25*a(n-1)*a(n-3) - 29*a(n-2)^2)/a(n-4), n>=4.
MATHEMATICA
Join[{1, 1, -4, -129}, RecurrenceTable[{a[n] == (25*a[n - 1]*a[n - 3] - 29*a[n - 2]^2)/a[n - 4], a[4] == -3689, a[5] == -113689, a[6] == 7001471, a[7] == 7911171596}, a, {n, 4, 25}]] (* G. C. Greubel, Aug 14 2018 *)
nxt[{a_, b_, c_, d_}]:={b, c, d, (25d*b-29c^2)/a}; NestList[nxt, {1, 1, -4, -129}, 20][[All, 1]] (* Harvey P. Dale, Aug 04 2022 *)
PROG
(Magma) I:=[-3689, -113689, 7001471, 7911171596]; [1, 1, -4, -129] cat [n le 4 select I[n] else (25*Self(n-1)*Self(n-3) - 29*Self(n-2)^2 )/Self(n-4): n in [1..30]]; // G. C. Greubel, Aug 14 2018
CROSSREFS
Sequence in context: A305568 A057134 A041495 * A298274 A299136 A117897
KEYWORD
sign,easy
AUTHOR
Paul Barry, Mar 28 2011
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 31 22:36 EDT 2023. Contains 363068 sequences. (Running on oeis4.)