%N Numbers a(n) such that if n is prime, a(n) is the n-th prime number and if n is not prime, a(n) is the n-th nonprime number (A002808).
%e a(1) is the first nonprime: 1.
%e a(2) is the second prime: 3.
%A Luc Stevens (lms022(AT)yahoo.com), Apr 11 2006
%E Definition corrected by _Michel Marcus_, Jun 01 2013