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A225493 Numbers having only strong prime factors, cf. A051634.

%I A225493 #8 Mar 17 2018 04:08:03
%S A225493 1,11,17,29,37,41,59,67,71,79,97,101,107,121,127,137,149,163,179,187,
%T A225493 191,197,223,227,239,251,269,277,281,289,307,311,319,331,347,367,379,
%U A225493 397,407,419,431,439,451,457,461,479,487,493,499,521,541,557,569,587
%N A225493 Numbers having only strong prime factors, cf. A051634.
%H A225493 Reinhard Zumkeller, <a href="/A225493/b225493.txt">Table of n, a(n) for n = 1..5000</a>
%F A225493 Multiplicative closure of A051634.
%o A225493 (Haskell)
%o A225493 import Data.Set (singleton, fromList, union, deleteFindMin)
%o A225493 a225493 n = a225493_list !! (n-1)
%o A225493 a225493_list = 1 : h (singleton p) ps [p] where
%o A225493    (p:ps) = a051634_list
%o A225493    h s xs'@(x:xs) ys
%o A225493      | m > x     = h (s `union` (fromList $ map (* x) (1 : ys))) xs ys
%o A225493      | otherwise = m : h (s' `union` (fromList $ map (* m) ys')) xs' ys'
%o A225493      where ys' = m : ys; (m, s') = deleteFindMin s
%Y A225493 Cf. A225494 (balanced), A225495 (weak), A225496 (non-balanced).
%K A225493 nonn
%O A225493 1,2
%A A225493 _Reinhard Zumkeller_, May 09 2013