a(1) = 1 and thereafter a(n) = a(n-1) + j(n-1) where j(1) = 1 and then j(n) = j(n-1)-1 if a(n) is composite or j(n) = 2*j(n-1) if a(n) is prime.

A382671

a(1) = 1 and thereafter a(n) = a(n-1) + j(n-1) where j(1) = 1 and then j(n) = j(n-1)-1 if a(n) is composite or j(n) = 2*j(n-1) if a(n) is prime.