|
| |
|
|
A171638
|
|
Denominator of 1/(n-2)^2 -1/(n+2)^2.
|
|
1
|
|
|
|
0, 25, 9, 441, 64, 2025, 225, 5929, 576, 13689, 1225, 27225, 2304, 48841, 3969, 81225, 6400, 127449, 9801, 190969, 14400, 275625, 20449, 385641, 28224, 525625, 38025, 700569, 50176, 915849, 65025, 1177225, 82944, 1490841
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
2,2
|
|
|
COMMENTS
|
Fifth column of an array of denominators related to the energies of the hydrogen spectrum, mentioned in A171522. At n=2, the defining formula has a pole and is replaced by 0 to conform with A171621 and A099761.
|
|
|
LINKS
|
Table of n, a(n) for n=2..35.
Index to sequences with linear recurrences with constant coefficients, signature (0,5,0,-10,0,10,0,-5,0,1)
|
|
|
FORMULA
|
a(n)= (A171621(n))^2.
a(2n+2) = A099761(n).
|
|
|
MAPLE
|
A061037 := proc(n) 1/4-1/n^2 ; numer(%) ; end proc:
A171621 := proc(n) if n mod 4 = 2 then 4*A061037(n) ; else A061037(n) ; end if; end proc:
A171638 := proc(n) A171621(n)^2 ; end proc:
seq(A171638(n), n=2..90) ; # R. J. Mathar, Apr 02 2011
|
|
|
PROG
|
(MAGMA) [0] cat [Denominator((1/(n-2)^2 -1/(n+2)^2)): n in [3..350]]; // Bruno Berselli, Apr 05 2011
|
|
|
CROSSREFS
|
Sequence in context: A215539 A224490 A181763 * A217432 A040604 A097440
Adjacent sequences: A171635 A171636 A171637 * A171639 A171640 A171641
|
|
|
KEYWORD
|
nonn,frac,easy
|
|
|
AUTHOR
|
Paul Curtz, Dec 13 2009
|
|
|
STATUS
|
approved
|
| |
|
|
