[seqfan] Re: help needed for number of 2-covers

RGWv rgwv at rgwv.com
Sun Jul 3 19:02:21 CEST 2011


    This works but if is not elegant.
f[n_] := FullSimplify[(n!/E)*Sum[(1/m!)*Sum[(-1/2)^k*Binomial[m*(m - 1)/2, 
n - k]/k!, {k, 0, n}], {m, 0, Infinity}]]


-----Original Message----- 
From: N. J. A. Sloane
Sent: Sunday, July 03, 2011 11:46 AM
To: seqfan at list.seqfan.eu
Subject: [seqfan] Re: help needed for number of 2-covers

Robert, Thanks for this!

> That is A060053.
(used only m<1000 for small n values to get v_n for small n values).

I have now edited A060053 to add the new reference.

Unfortunately there is no Maple or Mma program for that entry!
And no b-file. Could you add either?



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