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A104289 Number of primes between n*p(n) and n*p(n+1). 1
0, 1, 2, 5, 2, 5, 2, 6, 9, 2, 11, 8, 3, 9, 12, 14, 6, 13, 12, 9, 18, 11, 17, 23, 9, 7, 14, 8, 16, 52, 14, 23, 6, 40, 8, 26, 24, 22, 27, 26, 6, 45, 13, 19, 8, 63, 60, 21, 9, 18, 34, 13, 56, 35, 33, 36, 12, 37, 24, 13, 62, 81, 31, 16, 26, 97, 37, 67, 15, 24, 43, 59, 41, 47, 37, 44, 58 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Case n=1 is degenerate as 1p(1)=2, 1p(2)=3 and between 2 and 3 there is no prime while (PrimePi[n Prime[n+1]]-PrimePi[n Prime[n]]/.n->1)gives 1.

LINKS

Table of n, a(n) for n=1..77.

EXAMPLE

a(4)=5 because between 4p(4)=4*7=28 and 4p(5)=4*11=44, there are exactly 5 primes: 29,31,37,41,43.

MATHEMATICA

A104289=Prepend[Table[PrimePi[n Prime[n+1]]-PrimePi[n Prime[n]], {n, 2, 100}], 0]

CROSSREFS

Cf. A102820.

Sequence in context: A021400 A059855 A082881 * A177435 A087272 A299963

Adjacent sequences:  A104286 A104287 A104288 * A104290 A104291 A104292

KEYWORD

nonn

AUTHOR

Zak Seidov, Feb 28 2005

STATUS

approved

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Last modified March 18 17:51 EDT 2019. Contains 321292 sequences. (Running on oeis4.)