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.

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, 16, 50, 28, 7, 56, 22, 26, 48, 45, 51, 54, 32, 60, 57, 63, 66, 34, 38, 70, 49, 77, 84, 44, 46, 52, 72, 69, 75, 78, 58, 29, 116, 80, 90, 81, 96, 62, 64, 68, 98, 88, 11, 110, 74, 76, 82, 86