OFFSET
0,2
MAPLE
A013515 := proc(n)
sech(sec(x)-sech(x)) ;
coeftayl( %, x=0, 4*n) ;
%*(4*n)! ;
end proc: # R. J. Mathar, Dec 16 2011
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved