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A227911 Number of remainders occuring only once when dividing n by 1,2,...n. 0
1, 0, 1, 1, 1, 2, 2, 2, 3, 2, 2, 4, 4, 4, 5, 4, 4, 5, 5, 6, 7, 6, 6, 7, 7, 6, 7, 7, 7, 9, 9, 9, 10, 9, 9, 10, 10, 10, 11, 10, 10, 12, 12, 13, 14, 13, 13, 14, 14, 13, 14, 14, 14, 15, 15, 15, 16, 15, 15, 17, 17, 17, 18, 17, 17, 18, 18, 19, 20, 19, 19, 20, 20, 20, 21, 21, 21, 22, 22, 22, 23, 22, 22, 24, 24, 23 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

Number of 1's in row n of A072528.

LINKS

Table of n, a(n) for n=1..86.

EXAMPLE

9 divided by 1,2...9 gives the remainders 0,1,0,1,4,3,2,1,0 of which 2,3,4 occur only once, so a(9)=3.

PROG

(PARI) a(n)=v=vector(n+1); for(d=1, n, t=(n%d)+1; v[t]=v[t]+1); sum(i=1, n, v[i]==1)

CROSSREFS

Sequence in context: A290978 A142240 A284565 * A325783 A048288 A050677

Adjacent sequences:  A227908 A227909 A227910 * A227912 A227913 A227914

KEYWORD

nonn

AUTHOR

Ralf Stephan, Oct 13 2013

STATUS

approved

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Last modified June 24 09:37 EDT 2019. Contains 324323 sequences. (Running on oeis4.)