A178850 Lexicographically earliest infinite sequence such that (a(i)-a(j)) mod (a(k)-a(j)) is nonzero whenever i,j,k are disjoint.

1, 3, 6, 10, 20, 32, 112, 184, 232, 268, 364, 508, 2308, 3028, 5332, 8212, 46372, 75892, 106852, 116212, 191812, 222052, 265252, 298372, 315652, 328612, 361012, 401332, 444532, 507172, 635332, 706612, 787252, 943492, 1147252, 1210612, 1270372

Offset

1,2

Comments

First infinite picket-fence sequence: a picket fence extended from any pair in the set encounters no other member of the set.

Terms in this sequence gradually become restricted in increasing moduli. From a(7) on, all terms are == 4 (mod 12).

Links

Table of n, a(n) for n=1..37.

Example

From the initial 1,3, no further terms can be odd. After 3,6, no further multiples of 3 are possible. After 1,3,6, an 8 would be legal, except that no further extension of the sequence is then possible.

Crossrefs

Cf. A178758.

Sequence in context: A058356 A270048 A295719 * A018171 A306357 A365694

Adjacent sequences: A178847 A178848 A178849 * A178851 A178852 A178853

Keyword

nonn

Author

Franklin T. Adams-Watters, Jun 18 2010

Extensions

More terms from Jon E. Schoenfield, Jun 25 2010

Status

approved