A138561 Start with the list {1}; for each n >= 1, append p(n) primes followed by c(n) composite numbers, where p(n) is the n-th prime and c(n) is the n-th composite number.

1, 2, 3, 4, 6, 8, 9, 5, 7, 11, 10, 12, 14, 15, 16, 18, 13, 17, 19, 23, 29, 20, 21, 22, 24, 25, 26, 27, 28, 31, 37, 41, 43, 47, 53, 59, 30, 32, 33, 34, 35, 36, 38, 39, 40, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 42, 44, 45, 46, 48, 49, 50, 51, 52, 54, 109, 113, 127, 131

Offset: 1

Author

Amarnath Murthy, Mar 25 2008

Keywords

• easy
• nonn

Comments

A rearrangement of the natural numbers.

Examples

			We start with 1; p(1) = 2 is the first prime and the next two terms are 2,3 while c(1)=4 is the first composite number and the next four terms are 4,6,8,9 and so on.
		

Extensions

More terms from Sean A. Irvine, Apr 13 2010