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A218124 Number of 7-ary sequences with primitive period n. 2
1, 7, 42, 336, 2352, 16800, 117264, 823536, 5762400, 40353264, 282458400, 1977326736, 13841167200, 96889010400, 678222249264, 4747561492800, 33232924804800, 232630513987200, 1628413557439536, 11398895185373136, 79792266015134400, 558545864082460128 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..400

FORMULA

a(n) = Sum_{d|n} 7^d * mu(n/d) for n>0, a(0) = 1.

MAPLE

with(numtheory):

a:= n-> `if`(n=0, 1, add(7^d *mobius(n/d), d=divisors(n))):

seq(a(n), n=0..30);

CROSSREFS

Column k=7 of A143324.

Sequence in context: A271427 A073506 A025593 * A048862 A208943 A209071

Adjacent sequences:  A218121 A218122 A218123 * A218125 A218126 A218127

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Oct 21 2012

STATUS

approved

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Last modified October 16 12:35 EDT 2018. Contains 316263 sequences. (Running on oeis4.)