A179371 a(1) = 1; a(n) = smallest positive integer not already used which has a prime signature different from both a(n-1) and a(n-1)+1.

1, 4, 6, 8, 2, 9, 3, 10, 12, 14, 5, 16, 15, 7, 18, 21, 11, 22, 20, 13, 24, 17, 25, 19, 26, 23, 27, 29, 28, 30, 32, 31, 33, 36, 34, 37, 40, 35, 41, 38, 42, 39, 43, 46, 44, 47, 45, 48, 50, 49, 51, 53, 52, 54, 59, 55, 60, 56, 61, 63, 57, 64, 66, 58, 68, 67, 62, 70, 65, 71, 69, 72

Offset

1,2

Links

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

Example

To compute a(2), we see a(1) is 1; we look for the smallest unused positive integer that does not have the same prime signature as either 1 or 2. The first such number is 4.

Crossrefs

Cf. A179372

Sequence in context: A200366 A217296 A330154 * A097455 A201520 A179022

Adjacent sequences: A179368 A179369 A179370 * A179372 A179373 A179374

Keyword

nonn

Author

Will Nicholes, Jul 11 2010

Status

approved