A269795 - OEIS

A269795

Number of similarity classes of vectors with minimal Ducci period n.

2, 0, 6, 2, 30, 24, 126, 28, 504, 480, 2046, 990, 8190, 8064, 32730, 4064, 131070, 130536, 524286, 261630, 2097018, 2095104, 8388606, 2096100, 33554400, 33546240, 134217216, 67100670, 536870910, 536837640, 2147483646, 134213632, 8589932538, 8589803520, 34359738210

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..35.

Ron Brown and Jonathan L. Merzel, The number of Ducci sequences with given period, Fibonacci Quart. 45 (2007), no. 2, 115-121.

MATHEMATICA

a[n_] := DivisorSum[n, MoebiusMu[n/#] * 2^(#-IntegerExponent[#, 2]) &]; Array[a, 35] (* Amiram Eldar, Aug 24 2023 *)

PROG

(PARI) a(n) = sumdiv(n, d, moebius(n/d)*2^(d-valuation(d, 2)));

CROSSREFS

Sequence in context: A294779 A049257 A054877 * A372016 A095834 A106828