|
Search: id:A024283
|
|
|
| A024283 |
|
Expansion of tan(x)^2/2. |
|
+0
4
|
|
| 0, 1, 8, 136, 3968, 176896, 11184128, 951878656, 104932671488, 14544442556416, 2475749026562048, 507711943253426176, 123460740095103991808, 35125800801971979943936, 11559592093904798920736768
(list; graph; listen)
|
|
|
OFFSET
|
0,3
|
|
|
COMMENT
|
Number of cyclically reverse alternating permutations of length 2n+1, cf. A024255. - Vladeta Jovovic (vladeta(AT)Eunet.yu), May 20 2007
|
|
REFERENCES
|
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 259, T(n,2).
|
|
EXAMPLE
|
(tan x)^2 = x^2 + 2/3*x^4 + 17/45*x^6 + 62/315*x^8 + ...
|
|
MATHEMATICA
|
Tan[ x ]^2/2 (* Even Part *)
|
|
CROSSREFS
|
A009764.
Cf. A009764, A000182. A diagonal of A059419.
Sequence in context: A132869 A036915 A049211 this_sequence A134053 A136472 A101388
Adjacent sequences: A024280 A024281 A024282 this_sequence A024284 A024285 A024286
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
R. H. Hardin (rhh(AT)cadence.com)
|
|
EXTENSIONS
|
Extended and signs tested 03/97.
|
|
|
Search completed in 0.002 seconds
|
