A083197 - OEIS

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.

%I #6 Jul 16 2015 21:45:05

%S 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,

%T 24,25,41,43,47,53,59,61,67,71,26,27,28,30,32,33,34,35,36,73,79,83,89,

%U 97,101,103,107,109,113,38,39,40,42,44,45,46,48,49,50,51,127,131,137

%N 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.

%C This sequence is a permutation of the natural numbers.

%e Triangle begins:

%e 1

%e 2 3

%e 4 6 8

%e 5 7 11 13

%e 9 10 12 14 15

%e 17 19 23 29 31 37

%e ...

%K nonn,tabl

%O 1,2

%A _Amarnath Murthy_, Apr 27 2003

%E Edited, corrected and extended by _Ray Chandler_, Jan 05 2009