OFFSET
2,1
COMMENTS
The differences between odd prime numbers are always even, so a(n) is well defined for n>=2.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 2..10000
FORMULA
a(n) = ( prime(2*n) - prime(n) ) / 2.
a(n) = A072473(n)/2.
MATHEMATICA
Table[(Prime[2 k] - Prime[k])/2, {k, 2, 60}]
PROG
(Sage) [(nth_prime(2*n)-nth_prime(n))/2 for n in (2..60)] # Bruno Berselli, Jun 15 2015
(Magma) [(NthPrime(2*n)-NthPrime(n))/2: n in [2..60]]; // Bruno Berselli, Jun 15 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Federico Provvedi, Jun 15 2015
STATUS
approved