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3^a(n) is the highest power of 3 dividing A000110(n).
2

%I #13 Sep 08 2022 08:46:05

%S 0,0,0,0,1,0,0,0,2,1,0,1,0,0,0,0,0,4,0,0,0,1,1,0,1,0,0,0,0,0,1,0,0,0,

%T 1,1,0,1,0,0,0,0,0,1,0,0,0,3,1,0,1,0,0,0,0,0,2,0,0,0,1,1,0,1,0,0,0,0,

%U 0,1,0,0,0,1,1,0,1,0,0,0,0,0,1,0,0,0,2,1,0,1,0,0,0,0,0,2,0,0,0,1,1

%N 3^a(n) is the highest power of 3 dividing A000110(n).

%C This is the 3-adic valuation of the Bell numbers A000110.

%C The 2-adic valuation is less interesting: 0, 0, 1, 0, 0, 2, 0, 0, 2, 0, 0, 1, 0, 0, 1, 0, 0, 2, 0, 0, 2, 0, 0, 1, 0, 0, 1, 0, 0, 2, 0, 0, 2, 0, 0, 1, 0, 0, 1, 0, 0, 2, 0, 0, 2, ...

%H Amiram Eldar, <a href="/A227840/b227840.txt">Table of n, a(n) for n = 0..10000</a>

%t Table[IntegerExponent[BellB[n], 3], {n, 0, 100}] (* _Amiram Eldar_, Nov 23 2019 *)

%o (Magma) [Valuation(Bell(n), 3): n in [0..110]]; // _Bruno Berselli_, Aug 05 2013

%Y Cf. A000110, A007949.

%K nonn

%O 0,9

%A _N. J. A. Sloane_, Aug 05 2013