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A240592 Number of primes between successive composite squarefree numbers (A120944). 1
1, 2, 0, 2, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 0, 2, 0, 0, 1, 0, 2, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 2, 1, 0, 2, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 2, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 2, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

First positions where the numbers n=2..5 occur are at: 2, 142, 2180230, 256857823. - Vaclav Kotesovec, Apr 17 2014

LINKS

Table of n, a(n) for n=1..88.

EXAMPLE

a(4) is 2 because A120944(4)=15, A120944(5)=21, 2 primes between them: 17 and 19.

PROG

(PARI)

freesqrcomp(n)=issquarefree(n)&&!isprime(n)

nextfqc(n)={local(k); k=n+1; while(!freesqrcomp(k), k+=1); return(k)}

primesin(a, b)={local(p=a, q=0); while(p<b, p=nextprime(p); if(p<b, q+=1); p+=1); return(q)}

{for(i=2, 1000, if(freesqrcomp(i), m=nextfqc(i); p=primesin(i, m); print(p)))}

CROSSREFS

Cf. A120944, A240593.

Sequence in context: A266330 A219490 A277142 * A001877 A112712 A026608

Adjacent sequences:  A240589 A240590 A240591 * A240593 A240594 A240595

KEYWORD

nonn

AUTHOR

Antonio Roldán, Apr 08 2014

STATUS

approved

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Last modified July 25 04:48 EDT 2017. Contains 289779 sequences.