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a(n)=Sum_{j = 0..n} binomial(phi(n),phi(j)).
2

%I #5 Oct 15 2013 22:31:26

%S 2,3,6,7,22,8,74,29,90,30,1207,31,4118,121,466,467,67266,122,236984,

%T 496,7452,1973,3956273,497,1305399,8014,405387,8015,222108532,498,

%U 792121142,127353,1688345,127354,21495390,8511,66695906846,486580

%N a(n)=Sum_{j = 0..n} binomial(phi(n),phi(j)).

%t g[x_] := EulerPhi[x] Table[Apply[Plus, Table[Binomial[g[n], g[j]], {j, 0, n}]], {n, 1, 50}]

%Y Cf. A066781, A073318.

%K easy,nonn

%O 1,1

%A _Labos Elemer_, Jul 26 2002