A067649 Numerators of power series for sqrt(1+x^2)/sqrt(1-x).

1, 1, 7, 9, 43, 87, 387, 665, 8499, 17003, 72345, 131903, 913919, 1825875, 7629371, 14275257, 410980675, 820899123, 3396389533, 6448133283, 47448015653, 94775447369, 389689995525, 746772134927, 11150225818167, 22273876637759, 91192215965325, 175892149605307, 1326600896251559

Offset

0,3

Links

Robert Israel, Table of n, a(n) for n = 0..1663

Maple

S:= series(sqrt(1+x^2)/sqrt(1-x), x, 101):
seq(numer(coeff(S, x, j)), j=0..100); # Robert Israel, Apr 14 2021

Mathematica

Numerator[CoefficientList[Series[Sqrt[1+x^2]/Sqrt[1-x], {x, 0, 30}], x]] (* Stefano Spezia, Nov 21 2025 *)

Crossrefs

Denominators are given in A046161.

Sequence in context: A323676 A007449 A189053 * A025631 A258183 A038275

Adjacent sequences: A067646 A067647 A067648 * A067650 A067651 A067652

Keyword

nonn

Author

Benoit Cloitre, Feb 02 2002

Status

approved