

A144160


Number of pairs p,q with p < q such that 30*r(n)=p+q+2 and p p+2, q q+2 twin primes, r(i)=ith prime.


3



1, 2, 2, 6, 5, 4, 3, 3, 4, 6, 5, 4, 6, 9, 4, 6, 5, 5, 6, 11, 8, 10, 9, 6, 13, 6, 6, 9, 8, 13, 16, 10, 14, 14, 11, 11, 11, 8, 8, 7, 15, 14, 9, 13, 16, 12, 20, 16, 14, 13, 13, 15, 19, 19, 10, 15, 15, 15, 14, 18, 19, 21, 23, 12, 16, 15, 13, 21, 11, 26, 15, 19, 15, 15, 26, 18, 13, 13, 17, 20
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OFFSET

1,2


COMMENTS

The sequence is infinite: all numbers > 0 are present at least once and a(n) is always > 0.


LINKS

Pierre CAMI, Table of n, a(n) for n = 1..10000


EXAMPLE

30*2=60 17+43=19+41=60 17,19 and 41,43 twin primes r(1)=2 so a(1)=1 30*3=90 17+73=19+71=90 17,19 as 71,73 twin primes 29+61=31+59=90 29,31 as 59,61 twin primes, r(2)=3 so a(2)=2


CROSSREFS

Sequence in context: A209767 A122070 A181661 * A275142 A200226 A300628
Adjacent sequences: A144157 A144158 A144159 * A144161 A144162 A144163


KEYWORD

nonn


AUTHOR

Pierre CAMI, Sep 12 2008


STATUS

approved



