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A061498 Number of distinct terms in the first difference sequence of reduced residue system[=dRRS] for n. 6
0, 0, 1, 1, 1, 1, 1, 1, 2, 2, 1, 2, 1, 2, 3, 1, 1, 2, 1, 2, 3, 2, 1, 2, 2, 2, 2, 2, 1, 3, 1, 1, 3, 2, 3, 2, 1, 2, 3, 2, 1, 3, 1, 2, 3, 2, 1, 2, 2, 2, 3, 2, 1, 2, 3, 2, 3, 2, 1, 3, 1, 2, 3, 1, 3, 3, 1, 2, 3, 3, 1, 2, 1, 2, 3, 2, 3, 3, 1, 2, 2, 2, 1, 3, 3, 2, 3, 2, 1, 3, 3, 2, 3, 2, 3, 2, 1, 2, 3, 2, 1, 3, 1, 2, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,9

LINKS

Michael De Vlieger, Table of n, a(n) for n = 1..10000

EXAMPLE

For n=24, RRS={1, 5, 7, 11, 13, 17, 19, 23}, dRRS={4, 2, 4, 2, 4, 2, 4};

for n=32, dRRS={2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2};

for n=31, dRRS={1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...};

for n=34, RRS={1, 3, 5, 7, 9, 11, 13, 15, 19, 21, 23, 25, 27, 29, 31, 33}, dRRS={2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2};

so a(24)=2, a(32)=1, a(31)=1, a(34)=2.

MATHEMATICA

Table[Length@ Union@ Differences@ Select[Range@ n, CoprimeQ[#, n] &], {n, 105}] (* Michael De Vlieger, Jul 15 2017 *)

PROG

(PARI) a(n) = {my(va = select(x->(gcd(n, x)==1), [1..n])); vd = vector(#va-1, k, va[k+1] - va[k]); #Set(vd); } \\ Michel Marcus, Jul 08 2018

CROSSREFS

Cf. A076362.

Sequence in context: A024317 A024880 A029424 * A106029 A260311 A188431

Adjacent sequences:  A061495 A061496 A061497 * A061499 A061500 A061501

KEYWORD

nonn

AUTHOR

Labos Elemer, Jun 12 2001

STATUS

approved

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Last modified September 25 13:01 EDT 2020. Contains 337344 sequences. (Running on oeis4.)