A013324 Numerator of [x^n] of the Taylor series arccosh(exp(x)-tanh(x))= x+x^2/2 -x^3/8 -7*x^4/48 +3*x^5/128 +631*x^6/11520 +37*x^7/15360 -12731*x^8/645120 -...

1, 1, -1, -7, 3, 631, 37, -12731, -37481, 771163, 590381, -195597517, -8025539, -205204695149, 5456117628779, 3973785585851, -3056850228539, -168086791499223239

Offset

1,4

Comments

The e.g.f. at x/2 seems to admit an integer representation: arccosh(exp(x)-tanh(x)) = 2*x/(2*1!) +4*x^2/(2^2*2!) -6*x^3/(2^3*3!) -56*x^4/(2^4*4!) +90*x^5/(2^5*5!) +2524*x^6/(2^6*6!) ...

Links

Table of n, a(n) for n=1..18.

Crossrefs

Sequence in context: A086453 A320842 A112099 * A110792 A221388 A303982

Adjacent sequences: A013321 A013322 A013323 * A013325 A013326 A013327

Keyword

sign,frac

Author

Patrick Demichel (patrick.demichel(AT)hp.com)

Extensions

Values replaced by numerators. - R. J. Mathar, Dec 22 2011

Status

approved