|
|
A188315
|
|
A (25,-29) Somos-4 sequence.
|
|
3
|
|
|
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
|
|
|
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
|
|
|
KEYWORD
|
sign,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|