A081248 - OEIS

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A081248

Number of numbers k<=n with mu(k+n)+mu(k)=0, where mu=A008683 (Moebius function).

1, 1, 1, 3, 2, 1, 3, 4, 2, 3, 4, 6, 5, 2, 6, 9, 5, 5, 7, 9, 6, 7, 7, 9, 6, 6, 11, 14, 9, 6, 10, 18, 11, 8, 10, 20, 10, 12, 12, 21, 12, 6, 11, 25, 19, 14, 11, 22, 11, 16, 19, 27, 12, 16, 18, 28, 15, 17, 16, 23, 11, 16, 26, 32, 18, 16, 19, 34, 21, 18, 20, 43, 18, 23, 31, 41, 22, 16, 20, 45

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

LINKS

Table of n, a(n) for n=1..80.

EXAMPLE

n=10: mu(1+10)+mu(1)=(-1)+1, mu(5+10)+mu(5)=1+(-1), mu(8+10)+mu(8)=0+0 and mu(k+10)+mu(k)<>0 for k in {2,3,4,6,7,9,10}, therefore a(10)=3.

MATHEMATICA

Table[Total[Table[If[MoebiusMu[k+n]+MoebiusMu[n]==0, 1, 0], {n, k}]], {k, 80}] (* Harvey P. Dale, Oct 06 2017 *)

CROSSREFS

Cf. A081247.

Sequence in context: A238583 A238556 A102288 * A214636 A318582 A318317

Adjacent sequences: A081245 A081246 A081247 * A081249 A081250 A081251

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Mar 12 2003

STATUS

approved