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A218259 a(n) = |{m : multiplicative order of n mod m = 10}|. 2
0, 5, 16, 38, 47, 40, 66, 84, 150, 33, 72, 10, 106, 178, 168, 140, 265, 54, 534, 106, 68, 20, 296, 56, 564, 231, 732, 52, 730, 26, 604, 114, 80, 164, 348, 332, 297, 50, 912, 84, 904, 110, 88, 130, 222, 552, 332, 76, 1430, 81, 702, 236, 950, 178, 256, 168, 564 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = tau(n^10-1)-tau(n^5-1)-tau(n^2-1)+tau(n-1), with tau = A000005.

MAPLE

with(numtheory):

a:= n-> add(mobius(10/d) *tau(n^d-1), d={1, 2, 5, 10}):

seq(a(n), n=1..80);

CROSSREFS

Row n=10 of A212957.

Cf. A000005, A008683.

Sequence in context: A296536 A041044 A042645 * A211807 A174723 A011932

Adjacent sequences:  A218256 A218257 A218258 * A218260 A218261 A218262

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Oct 24 2012

STATUS

approved

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Last modified June 6 18:59 EDT 2020. Contains 334832 sequences. (Running on oeis4.)