A114263 - OEIS

A114263

Smallest number m such that prime(n) + 2*prime(n+m) is a prime.

1, 1, 1, 1, 1, 4, 5, 3, 2, 2, 3, 1, 1, 4, 5, 1, 5, 4, 2, 2, 2, 2, 1, 3, 1, 1, 8, 4, 1, 1, 2, 3, 9, 2, 5, 2, 2, 9, 6, 1, 1, 1, 1, 2, 3, 4, 1, 4, 5, 8, 11, 1, 11, 4, 5, 1, 4, 1, 5, 8, 1, 1, 1, 1, 2, 5, 1, 5, 9, 2, 1, 10, 3, 4, 4, 5, 5, 6, 7, 4, 1, 1, 2, 4, 13, 6, 6, 6, 7, 9, 1, 3, 1, 7, 3, 9, 1, 3, 3, 6, 3, 8, 2

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OFFSET

2,6

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 2..10000

EXAMPLE

n=2: prime(2)+2*prime(2+1)=3+2*5=13 is prime, so a(2)=1;

n=3: prime(3)+2*prime(3+1)=5+2*7=19 is prime, so a(2)=1;

...

n=7: prime(7)+2*prime(7+1)=17+2*19=55 is not prime

...

prime(7)+2*prime(7+4)=17+2*31=79 is prime, so a(7)=4;