A171709 Numerator of 1/9 - 1/n^2.

0, -5, -8, -1, -8, -5, 0, 7, 16, 1, 40, 55, 8, 91, 112, 5, 160, 187, 8, 247, 280, 35, 352, 391, 16, 475, 520, 7, 616, 667, 80, 775, 832, 11, 952, 1015, 40, 1147, 1216, 143, 1360, 1435, 56, 1591, 1672, 65, 1840, 1927, 224, 2107, 2200, 85, 2392, 2491, 32, 2695, 2800, 323, 3016, 3127, 40, 3355, 3472, 133, 3712

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

Cf. A067998.

Sequence in context: A263497 A198139 A247277 * A093157 A122998 A227158

Adjacent sequences: A171706 A171707 A171708 * A171710 A171711 A171712

Keyword

sign,easy,frac

Author

Paul Curtz, Dec 16 2009

Extensions

Offset set to -3 by R. J. Mathar, Nov 23 2010

Status

approved