A013515 - OEIS

A013515

sech(sec(x)-sech(x))=1-12/4!*x^4+1568/8!*x^8+6840768/12!*x^12...

1, -12, 1568, 6840768, -41485549312, -616649036623872, 51689032519042469888, 309411873154808535072768

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OFFSET

0,2

LINKS

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