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A013515
sech(sec(x)-sech(x))=1-12/4!*x^4+1568/8!*x^8+6840768/12!*x^12...
1
1, -12, 1568, 6840768, -41485549312, -616649036623872, 51689032519042469888, 309411873154808535072768
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
Sequence in context: A366832 A160237 A013474 * A159383 A015011 A271435
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved