OFFSET
3,3
LINKS
S. J. Cyvin et al., Theory of polypentagons, J. Chem. Inf. Comput. Sci., 33 (1993), 466-474
Index entries for linear recurrences with constant coefficients, signature (6,-10,-2,12,4,8,-48,32).
FORMULA
G.f. x^3+x^4+2*x^5+12*x^6 -x^7 *(12 -43*x +18*x^2 +52*x^3 +18*x^4 -32*x^5 -176*x^6 +160*x^7) / ( (2*x^2-1) *(2*x^3-1) *(2*x-1)^3 ). - R. J. Mathar, Jul 26 2019
MAPLE
A122745 := proc(n)
local a, d ;
if n < 5 then
1;
else
a := n-3 ;
if modp(a, 3) = 0 then
d := 1 ;
else
d := 0 ;
end if;
# note the typo in last exponent in (31b)
(a+2)*(a+7)*2^(a-5)/3+2^floor(a/2-2) ;
%+d*2^(floor((a-3)/3))/3 ;
end if;
end proc:
seq(A122745(n), n=3..30) ; # R. J. Mathar, Jul 26 2019
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Sep 24 2006
STATUS
approved