A082191 - OEIS

A082191

In a square array, positive integers are entered as follows. Start with a(1, 1)=1. Then enter numbers in this order: a(1, 2), a(2, 1), a(3, 1), a(2, 2), a(1, 3), a(1, 4), a(2, 3), a(3, 2), a(4, 1), a(5, 1), a(4, 2), ... such that every entry is the smallest not yet used and such that every entry greater than 1 has a common divisor with its neighbors (in all directions) which are greater than 1.

%I #8 Oct 02 2014 17:55:56

%S 1,2,4,6,8,10,5,20,12,3,9,15,18,30,25,35,40,14,21,24,27,33,36,39,42,

%T 16,50,28,7,56,22,26,48,45,51,54,32,60,57,63,66,34,38,70,49,77,84,44,

%U 46,52,72,69,75,78,58,29,116,80,90,81,96,62,64,68,98,88,11,110,74,76,82,86

%N In a square array, positive integers are entered as follows. Start with a(1, 1)=1. Then enter numbers in this order: a(1, 2), a(2, 1), a(3, 1), a(2, 2), a(1, 3), a(1, 4), a(2, 3), a(3, 2), a(4, 1), a(5, 1), a(4, 2), ... such that every entry is the smallest not yet used and such that every entry greater than 1 has a common divisor with its neighbors (in all directions) which are greater than 1.

%Y Cf. A082192, A082193, A082194, A082195.

%K nonn

%O 1,2

%A _Amarnath Murthy_, Apr 07 2003

%E Corrected and extended by _Matthew Conroy_, Sep 03 2007