A062974 Numbers k such that omega(k+1) < 2*omega(k), where omega(k) is the number of distinct prime divisors of k.

2, 3, 4, 6, 7, 8, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 26, 28, 30, 31, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100

Offset: 1

Author

Jason Earls, Jul 26 2001

Keywords

• nonn

Comments

A001221(a(n)+1) < 2*A001221(a(n)).

Links

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

Crossrefs

Cf. A006049 (subsequence).

Programs

Haskell

import Data.List (findIndices)
a062974 n = a062974_list !! (n-1)
a062974_list = map (+ 1) $ findIndices (< 0) $
   zipWith (-) (tail a001221_list) $ map (* 2) a001221_list
-- Reinhard Zumkeller, Jan 22 2013

PARI

j=[]; for(n=1,200, if(omega(n+1)<2*omega(n),j=concat(j,n))); j