A083197 Triangular array, read by rows, where if n is odd the n-th row consists of n least unused nonprimes, while if n is even the n-th row consists of the n least unused primes.

1, 2, 3, 4, 6, 8, 5, 7, 11, 13, 9, 10, 12, 14, 15, 17, 19, 23, 29, 31, 37, 16, 18, 20, 21, 22, 24, 25, 41, 43, 47, 53, 59, 61, 67, 71, 26, 27, 28, 30, 32, 33, 34, 35, 36, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50, 51, 127, 131, 137

Offset

1,2

Comments

This sequence is a permutation of the natural numbers.

Links

Table of n, a(n) for n=1..69.

Example

Triangle begins:
1
2 3
4 6 8
5 7 11 13
9 10 12 14 15
17 19 23 29 31 37
...

Crossrefs

Sequence in context: A166310 A293030 A109852 * A235262 A245704 A260425

Adjacent sequences: A083194 A083195 A083196 * A083198 A083199 A083200

Keyword

nonn,tabl

Author

Amarnath Murthy, Apr 27 2003

Extensions

Edited, corrected and extended by Ray Chandler, Jan 05 2009

Status

approved