OFFSET
0,5
COMMENTS
Run lengths in A173922.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,0,0,2)
FORMULA
a(n) = 2^floor(n/4).
G.f.: x*(1+x)*(1+x^2)/(1-2*x^4 ). - R. J. Mathar, Nov 21 2011
EXAMPLE
a(4) = 2^1 = 2.
MATHEMATICA
CoefficientList[Series[x*(1 + x)*(1 + x^2)/(1 - 2*x^4), {x, 0, 50}], x] (* or *) Table[2^(Floor[n/4]), {n, 0, 50}] (* G. C. Greubel, Apr 30 2017 *)
PROG
(PARI) a(n)=2^(n\4) \\ Charles R Greathouse IV, Oct 03 2016
(Python)
def A200675(n): return 1<<(n>>2) # Chai Wah Wu, Jan 30 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jeremy Gardiner, Nov 20 2011
EXTENSIONS
Offset corrected by Charles R Greathouse IV, Oct 03 2016
STATUS
approved