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

Offset

1,2

Links

Table of n, a(n) for n=1..72.

Crossrefs

Cf. A082192, A082193, A082194, A082195.

Sequence in context: A338741 A115950 A077127 * A319806 A055952 A061243

Adjacent sequences: A082188 A082189 A082190 * A082192 A082193 A082194

Keyword

nonn

Author

Amarnath Murthy, Apr 07 2003

Extensions

Corrected and extended by Matthew Conroy, Sep 03 2007

Status

approved