This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A131107 #2 Mar 30 2012 17:38:08 %S A131107 1,1,1,1,1,1,1,3,4,1,1,2,3,2,1,1,5,16,27,16,1,1,3,25,16,81,16,1,1,7, %T A131107 12,125,256,81,64,1,1,4,49,54,125,512,729,16,1,1,9,64,343,1296,3125, %U A131107 4096,2187,256,1,1,5,27,128,2401,1296,15625,2048,729,256,1,1,11,100,729,4096 %N A131107 Rectangular array read by antidiagonals: k objects are each put into one of n boxes, independently with equal probability. a(n, k) is the expected number of boxes with exactly one object (n, k >= 1). Sequence gives the denominators. %Y A131107 Cf. A131106 gives the numerators. %K A131107 easy,frac,nonn,tabl %O A131107 1,8 %A A131107 _David Wasserman_, Jun 15 2007