%I #10 Aug 24 2023 02:30:14
%S 2,0,6,2,30,24,126,28,504,480,2046,990,8190,8064,32730,4064,131070,
%T 130536,524286,261630,2097018,2095104,8388606,2096100,33554400,
%U 33546240,134217216,67100670,536870910,536837640,2147483646,134213632,8589932538,8589803520,34359738210
%N Number of similarity classes of vectors with minimal Ducci period n.
%H Ron Brown and Jonathan L. Merzel, <a href="http://www.fq.math.ca/Papers1/45-2/brown.pdf">The number of Ducci sequences with given period</a>, Fibonacci Quart. 45 (2007), no. 2, 115-121.
%t a[n_] := DivisorSum[n, MoebiusMu[n/#] * 2^(#-IntegerExponent[#, 2]) &]; Array[a, 35] (* _Amiram Eldar_, Aug 24 2023 *)
%o (PARI) a(n) = sumdiv(n, d, moebius(n/d)*2^(d-valuation(d, 2)));
%K nonn
%O 1,1
%A _Michel Marcus_, Mar 05 2016