OFFSET
1,1
EXAMPLE
For n=3, prime(3n) = 23, and prime(n) = 5, therefore a(3) = 23 - 5 = 18.
MATHEMATICA
Table[Prime[3n] - Prime[n], {n, 1, 100}]
PROG
(PARI) a(n) = prime(3*n) - prime(n); \\ Michel Marcus, Aug 18 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Terry D. Grant, Aug 15 2016
STATUS
approved