A090821 Numbers that are products of two consecutive nonprimes.

4, 24, 48, 72, 90, 120, 168, 210, 240, 288, 360, 420, 462, 528, 600, 650, 702, 756, 840, 960, 1056, 1122, 1190, 1260, 1368, 1482, 1560, 1680, 1848, 1980, 2070, 2208, 2352, 2450, 2550, 2652, 2808, 2970, 3080, 3192, 3306, 3480, 3720, 3906, 4032, 4160, 4290

Offset

1,1

Links

Table of n, a(n) for n=1..47.

Example

The nonprimes: 1,4,6,8,9,10,12,14,15 ..., product of consecutive nonprimes: 4,24,48,72,90,...

Mathematica

With[{nonps=Complement[Range[100], Prime[Range[PrimePi[100]]]]}, Times @@@ Partition[nonps, 2, 1]] (* Harvey P. Dale, Jan 16 2012 *)

Crossrefs

Cf. A018252.

Sequence in context: A080380 A364278 A039935 * A226575 A052645 A353250

Adjacent sequences: A090818 A090819 A090820 * A090822 A090823 A090824

Keyword

easy,nonn

Author

Felix Tubiana, Feb 11 2004

Extensions

Definition clarified by Harvey P. Dale, Jan 16 2012

Status

approved