OFFSET
-3,2
COMMENTS
A061039 extended to negative n. a(0)=-1 is defined at the pole where the expression is undefined.
LINKS
G. C. Greubel, Table of n, a(n) for n = -3..1000
FORMULA
a(n) = A061039(n), n>2.
a(n) = a(-n).
MAPLE
seq( `if`(n=0, -1, numer(1/9 -1/n^2)), n=-3..65); # G. C. Greubel, Nov 29 2019
MATHEMATICA
Table[If[n==0, -1, Numerator[1/9 -1/n^2]], {n, -3, 65}] (* G. C. Greubel, Nov 29 2019 *)
PROG
(PARI) a(n) = if(n==0, -1, numerator(1/9 -1/n^2)); \\ G. C. Greubel, Nov 29 2019
(Magma) [n eq 0 select -1 else Numerator(1/9 -1/n^2): n in [-3..65]]; // G. C. Greubel, Nov 29 2019
(Sage)
def a(n):
if (n==0): return -1
else: return numerator(1/9 -1/n^2)
[a(n) for n in (-3..65)] # G. C. Greubel, Nov 29 2019
CROSSREFS
KEYWORD
sign,easy,frac
AUTHOR
Paul Curtz, Dec 16 2009
EXTENSIONS
Offset set to -3 by R. J. Mathar, Nov 23 2010
STATUS
approved