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A297217 Most common value of the number of divisors function among all composites up to composite(n) inclusive, or 0 if there is a tie. 1
3, 0, 4, 0, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Is a(n) = 4 for all n > 4?

LINKS

Table of n, a(n) for n=1..87.

EXAMPLE

n | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12

-------------------------------------------------------------------------

A002808(n) | 4 | 6 | 8 | 9 | 10 | 12 | 14 | 15 | 16 | 18 | 20 | 21

-------------------------------------------------------------------------

A035004(n+1) | 3 | 4 | 4 | 3 | 4 | 6 | 4 | 4 | 5 | 6 | 6 | 4

-------------------------------------------------------------------------

a(n) | 3 | 0 | 4 | 0 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4

PROG

(PARI) composite(n) = my(i=0); forcomposite(c=1, , i++; if(i==n, return(c)))

mcv(v) = my(w=vecsort(v, , 8), count=vector(#w), ind=0, i=0); for(x=1, #w, for(y=1, #v, if(w[x]==v[y], count[x]++))); for(k=1, #count, if(count[k]==vecmax(count), ind=k; i++)); if(i > 1, return(0), return(w[ind]))

a(n) = my(v=[]); for(k=1, n, v=concat(v, numdiv(composite(k)))); mcv(v)

CROSSREFS

Cf. A002808, A035004.

Sequence in context: A340426 A308717 A359866 * A218859 A246691 A066705

Adjacent sequences: A297214 A297215 A297216 * A297218 A297219 A297220

KEYWORD

nonn,easy

AUTHOR

Felix Fröhlich, Mar 02 2018

STATUS

approved

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Last modified March 20 21:56 EDT 2023. Contains 361391 sequences. (Running on oeis4.)