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%I #16 May 20 2018 12:39:38
%S 1,2,2,3,3,4,4,4,4,6,6,6,7,8,8,9,8,10,8,10,11,12,12,12,13,12,12,15,15,
%T 16,14,14,14,15,16,19,18,18,18,21,19,22,21,22,23,24,24,24,22,24,25,27,
%U 23,25,24,25,29,29,28,31,31,32,30,28,29,33,31,32,34,36,35,37,36,35,36
%N Number of classes generated by function A007947 when applied to binomial coefficients.
%e For n=9, A007947({C(9,k)}) = {1,3,6,42,42,42,42,6,3,1} includes 4 distinct values, thus generating 4 classes of k values: {0,9}, {1,8}, {2,7} and {3,4,5,6}. So a(9)=4.
%t a[n_] = Length[ Union[ Table[ A007947[ binomial[ n, k ] ], {k, 0, n} ] ] ]
%o (PARI) a(n) = #Set(vector(ceil(n\2)+1, k, factorback(factorint(binomial(n,k-1))[, 1]))); \\ _Michel Marcus_, May 20 2018
%Y Cf. A007947, A080396.
%K nonn
%O 1,2
%A _Labos Elemer_
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