

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
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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 * A309697 A177435 A087272
Adjacent sequences: A104286 A104287 A104288 * A104290 A104291 A104292


KEYWORD

nonn


AUTHOR

Zak Seidov, Feb 28 2005


STATUS

approved



