A066681 Badly sieved numbers (A066680) which are not primes.

8, 12, 18, 27, 30, 45, 50, 63, 70, 75, 80, 98, 105, 112, 125, 128, 147, 154, 165, 168, 175, 176, 182, 192, 195, 208, 220, 231, 242, 245, 260, 264, 273, 275, 286, 312, 325, 338, 340, 343, 357, 363, 374, 380, 385, 396, 399, 408

Offset

1,1

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Index entries for sequences generated by sieves

Formula

A099104(a(n))*A005171(a(n)) = 1. [Reinhard Zumkeller, Nov 12 2009]

Example

8 is the first nonprime in A066680, as multiples of 2 are marked only up to 4 = 2^2 and all other multiples of unmarked numbers < 8 do not hit 8.

Prog

(Haskell)
a066681 n = a066681_list !! (n-1)
a066681_list = filter ((== 0) . a010051) a066680_list
-- Reinhard Zumkeller, Feb 17 2012

Crossrefs

Cf. A010051.

Sequence in context: A087696 A293529 A028393 * A276403 A171241 A120137

Adjacent sequences: A066678 A066679 A066680 * A066682 A066683 A066684

Keyword

nonn

Author

Reinhard Zumkeller, Dec 31 2001

Status

approved