Addition theorem for gegenbauer poly

[Useful nucleus]

Please , can you help in finding the addition theorem of gegenbauer polynomials on the web?

many thanks

 

[arildno]

There were lots of references when googling.
Most seemed to be journal-locked, though.

You might start with what mathworld has to say about the creatures:
http://mathworld.wolfram.com/GegenbauerPolynomial.html

 

[Useful nucleus]

thanks for help!