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%I #20 Sep 26 2018 21:43:29
%S -1,-15,-3,-7,0,9,5,33,3,65,21,105,1,153,45,209,15,273,77,345,3,425,
%T 117,513,35,609,165,713,3,825,221,945,63,1073,285,1209,5,1353,357,
%U 1505,99,1665,437,1833,15,2009,525,2193,143,2385,621,2585,21,2793,725,3009,195,3233,837,3465,14,3705
%N Numerator of 1/16 - 1/n^2, using -1 at the pole where n=0.
%C Extends the Brackett spectrum to negative principal quantum numbers in the spirit of A144477 and A171709.
%H G. C. Greubel, <a href="/A174680/b174680.txt">Table of n, a(n) for n = 0..10000</a>
%F a(n) = A061041(n), n >= 4.
%F a(n) = A172157(4,n), n >= 1.
%F a(n) = a(-n) for all n in Z.
%t Table[(n^2 - 16)/(GCD[n^2 - 16, 16*n^2]), {n, 0, 100}] (* _G. C. Greubel_, Sep 16 2018 *)
%o (PARI) {a(n) = (n^2 - 16) / gcd(n^2 - 16, 16 * n^2)}; /* _Michael Somos_, Jan 06 2011 */
%Y Cf. A174233, A067998.
%K sign,easy
%O 0,2
%A _Paul Curtz_, Nov 30 2010
%E removed a(-4)-a(-1) since a(-n)=a(n) by _Michael Somos_, Jan 06 2011
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