login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A273047 E.g.f.: sqrt(-1+sqrt(1+3*cos(2*x)^2))/cos(2*x) [even terms only]. 1
1, 1, 2, -149, -14743, -1291124, -75141463, 16904078101, 12079897715342, 5127055781374651, 1591577436442791797, 16734787827095948776, -636181884940159502862223, -835452999214833112556297399, -749352506033895636346796223718, -390445159197257248842601279581749 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
The odd power terms are zero because the e.g.f. is even.
LINKS
EXAMPLE
1 + 1*x^2/2! + 2*x^4/4! - 149*x^6/6! - ...
PROG
(PARI)
x = 'x + O('x^31);
v = Vec(serlaplace(sqrt(-1+sqrt(1+3*cos(2*x)^2))/cos(2*x)));
vector((#v+1)\2, k, v[2*k-1])
CROSSREFS
Sequence in context: A062596 A142415 A068987 * A209077 A141139 A141130
KEYWORD
sign
AUTHOR
Gheorghe Coserea, May 13 2016
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 20 09:30 EDT 2024. Contains 371799 sequences. (Running on oeis4.)