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A243016 Number of solutions for k*n/(k+n) = p for integer k > 0 and prime p. 0
0, 0, 1, 2, 0, 3, 0, 1, 0, 1, 0, 2, 0, 2, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 2, 0, 1, 0, 1, 0, 0, 0, 2, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 2, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 2, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

It is unknown whether a(6) = 3 is the highest number in this sequence.

LINKS

Table of n, a(n) for n=1..92.

EXAMPLE

4*k/(4+k) has two solutions: k=4,p=2 and k=12,p=3. Thus a(4) = 2.

PROG

(PARI) a(n) = {t=0; for(k=1, n*(n-1), s=k*n/(k+n); if(floor(s)==s, if(ispseudoprime(s), t+=1))); return(t); }

n=1; while(n<100, print1(a(n), ", "); n+=1)

CROSSREFS

Sequence in context: A175663 A240672 A352288 * A284975 A219202 A341980

Adjacent sequences:  A243013 A243014 A243015 * A243017 A243018 A243019

KEYWORD

nonn

AUTHOR

Derek Orr, May 29 2014

STATUS

approved

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Last modified August 10 04:49 EDT 2022. Contains 356029 sequences. (Running on oeis4.)