A107391 Expansion of e.g.f. sin(x)^2 * sinh(x)^2.

24, -896, 67584, -4161536, 268959744, -17171480576, 1099645845504, -70366596694016, 4503633987108864, -288229826395897856, 18446752869802573824, -1180591479979922948096, 75557865977714137104384

Offset

1,1

Comments

The sequence contains each 4th term of the e.g.f. sin(x)^2*sinh(x)^2 = (24/4!)*x^4 - (896/8!)*x^8 + (67584/12!)*x^12 + ... - R. J. Mathar, Dec 17 2017

Links

Table of n, a(n) for n=1..13.

Index entries for linear recurrences with constant coefficients, signature (-48,1024).

Formula

a(n) = (1/2)*16^n - (1/4)*(-64)^n. [Corrected by Delbert L. Johnson, Mar 11 2023]

G.f.: 8*x*(3+32*x)/((1-16*x)*(1+64*x)).

Crossrefs

Sequence in context: A109575 A160111 A227666 * A281778 A006147 A061236

Adjacent sequences: A107388 A107389 A107390 * A107392 A107393 A107394

Keyword

sign,easy

Author

Ralf Stephan, May 25 2005

Status

approved