A178758 Smallest range 1..a(n) that permits n integers x() in 1..a(n) to exist with (x(i)-x(j)) mod (x(k)-x(j)) nonzero whenever i,j,k are disjoint.

1, 2, 6, 8, 18, 21, 33, 38, 54, 66, 83, 89, 106, 124, 150, 166, 190, 208, 232, 250

Offset

1,2

Comments

Maximal non-interfering picket-fence seeds: a picket fence extended from any pair in the set encounters no other member of the set

Links

Table of n, a(n) for n=1..20.

Example

a(1) 1
a(2) 1 2
a(3) 1 3 6
a(4) 1 3 6 8
a(5) 1 4 8 14 18
a(6) 1 4 8 14 18 21
a(7) 1 4 8 14 23 30 33
a(8) 1 5 11 15 24 28 34 38
a(9) 1 10 16 20 23 27 33 42 54
a(10) 1 7 11 17 26 32 40 52 60 66
a(11) 1 7 15 21 30 36 46 58 68 74 83
a(12) 1 7 15 21 30 36 46 58 68 74 83 89
a(13) 1 9 15 24 30 40 52 67 77 83 92 98 106
a(14) 1 10 22 30 36 51 57 68 74 89 95 103 115 124
a(15) 1 7 22 28 36 48 56 69 81 98 107 113 122 138 150
a(16) 1 7 15 27 45 59 65 74 93 102 108 122 140 152 160 166
a(17) 1 13 29 35 44 51 63 81 92 110 122 129 138 144 160 172 190
a(18) 1 19 31 47 53 62 69 81 99 110 128 140 147 156 162 178 190 208
a(19) 1 13 24 33 45 63 75 84 100 115 131 140 152 170 182 191 202 214 232
a(20) 1 19 31 42 51 63 81 93 102 118 133 149 158 170 188 200 209 220 232 250
(lexicographically earliest solutions)

Crossrefs

Sequence in context: A370864 A005823 A259026 * A024431 A152598 A154610

Adjacent sequences: A178755 A178756 A178757 * A178759 A178760 A178761

Keyword

nonn

Author

R. H. Hardin Jun 10 2010

Status

approved