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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, 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

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Last modified July 20 09:46 EDT 2024. Contains 374445 sequences. (Running on oeis4.)