OFFSET
0,2
COMMENTS
Cell configuration converges to a fractal with dimension 2.647...
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..750
Peter Karpov, InvMem, Item 26
Peter Karpov, Illustration of initial terms (n = 1..4)
Index entries for linear recurrences with constant coefficients, signature (28,-195,324).
FORMULA
a(0) = 1, a(1) = 21, a(2) = 399, a(n) = 28*a(n-1) - 195*a(n-2) + 324*a(n-3).
G.f.: (1-7*x+6*x^2)/(1-28*x+195*x^2-324*x^3).
MATHEMATICA
LinearRecurrence[{28, -195, 324}, {1, 21, 399}, 20]
PROG
(Magma) I:=[1, 21, 399]; [n le 3 select I[n] else 28*Self(n-1) - 195*Self(n-2) + 324*Self(n-3) : n in [1..41]]; // G. C. Greubel, Dec 10 2021
(Sage)
def A285396_list(prec):
P.<x> = PowerSeriesRing(ZZ, prec)
return P( (1-7*x+6*x^2)/(1-28*x+195*x^2-324*x^3) ).list()
A285396_list(40) # G. C. Greubel, Dec 10 2021
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Peter Karpov, Apr 19 2017
STATUS
approved