A013478 E.g.f. -arctanh(cos(x)-cosh(x)), coefficients of (4*i+2) only.

2, 242, 735842, 12696924242, 729261623797442, 105330801708282667442, 32155390653420235027326242, 18430773614710132775756232045842, 18200656974294045189446138614387578242, 29009142008847262758691664682458471045155442

Offset

0,1

Links

Matthew House, Table of n, a(n) for n = 0..112

Formula

a(n) = (4i+2)! * [x^(4i+2)] -arctanh(cos(x)-cosh(x)).

Maple

g := taylor(-arctanh(cos(x)-cosh(x)), x=0, 100):q := seq((coeff(g, x, 4*i+2)*(4*i+2)!), i=0..15);

Prog

(PARI) my(x = xx + O(xx^60)); v = Vec(serlaplace(-atanh(cos(x)-cosh(x)))); vector(#v\4, i, v[4*i+1]) \\ Michel Marcus, Jul 28 2015

Crossrefs

Sequence in context: A013509 A013472 A013505 * A049333 A140162 A145712

Adjacent sequences: A013475 A013476 A013477 * A013479 A013480 A013481

Keyword

nonn

Author

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

Extensions

More terms from Sascha Kurz, Mar 24 2002

a(0)=2 inserted by Alois P. Heinz, Jul 28 2015

Status

approved