Problem arduino

anna@AnnasDator:~$ sudo apt-get install arduino-core
[sudo] password for anna:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
  avr-libc avrdude binutils-avr gcc-avr libftdi1
Suggested packages:
  arduino-mk avrdude-doc task-c-devel gcc-doc gcc-4.2
The following NEW packages will be installed:
  arduino-core avr-libc avrdude binutils-avr gcc-avr libftdi1
0 upgraded, 6 newly installed, 0 to remove and 2 not upgraded.
Need to get 863 kB/24,9 MB of archives.
After this operation, 84,9 MB of additional disk space will be used.
Do you want to continue [Y/n]? y
WARNING: The following packages cannot be authenticated!
  libftdi1 binutils-avr gcc-avr avrdude avr-libc arduino-core
Install these packages without verification [y/N]? y
Err http://se.archive.ubuntu.com/ubuntu/ raring/universe arduino-core all 1:1.0.3+dfsg-2
  404  Not Found [IP: 130.239.18.173 80]
Failed to fetch http://se.archive.ubuntu.com/ubuntu/pool/universe/a/arduino/arduino-core_1.0.3+dfsg-2_all.deb  404  Not Found [IP: 130.239.18.173 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?