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Given a sequence of complex numbers $a_n$ with $n\in\mathbb{N}$, is it possible to find an analytic (or meromorphic) function that interpolates this sequence in the sense that $f(n)=a_n$?

If this is not always possible, what sort of conditions on the sequence could guarantee the existence of such an $f$?

flag	asked Dec 1 2009 at 1:07 Enrique 469●3●11

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See mathoverflow.net/questions/2944 – Yemon Choi Dec 1 2009 at 1:12

Ben Weiss · Answer 1 · 2009-12-01 01:23:34Z UTC

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There is a classic result of Ramanujan known as his Master Formula which Wolfram has here:

http://mathworld.wolfram.com/RamanujansInterpolationFormula.html

To summarize briefly (and coarsely): if the values you want to interpolate do not grow faster than the gamma function, things will be ok. If they do grow faster than that, his formula doesn't converge, so you'll have to find another technique.

answered Dec 1 2009 at 1:23

Ben Weiss
957●10●19

There are other references easily available on the web, hopefully a search for Ramanujan's master formula--maybe on MathSciNet--will help you find anything you need. – Ben Weiss Dec 1 2009 at 1:26

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It seems Google of Ramanujan "master theorem" works better than Ramanujan "master formula" – Gerald Edgar Dec 1 2009 at 13:09

Interpolation of sequences by analytic functions

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