OFFSET
0,3
COMMENTS
a(3*k+1) = (k+1)^3 for k >= 0.
REFERENCES
J. H. Conway and R. K. Guy, The Book of Numbers, Copernicus Press, NY, 1996. Sequence can be seen in the successive circled numbers at the top of page 64.
FORMULA
a(n) = n if n mod 3 = 0, = ((n+2)/3)^3 if n mod 3 = 1, and otherwise (n+1)^2/3.
MAPLE
f:=proc(n) if (n mod 3) = 0 then n
elif (n mod 3) = 1 then ((n+2)/3)^3;
else (n+1)^2/3; fi; end;
[seq(f(n), n=0..100)];
PROG
(Python)
def A346005(n): return n if n % 3 == 0 else ((n+2)//3)**3 if n % 3 == 1 else (n+1)**2//3 # Chai Wah Wu, Jul 25 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jul 25 2021
STATUS
approved