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A225494
Numbers having only balanced prime factors, cf. A006562.
5
1, 5, 25, 53, 125, 157, 173, 211, 257, 263, 265, 373, 563, 593, 607, 625, 653, 733, 785, 865, 947, 977, 1055, 1103, 1123, 1187, 1223, 1285, 1315, 1325, 1367, 1511, 1747, 1753, 1865, 1907, 2287, 2417, 2677, 2809, 2815, 2903, 2963, 2965, 3035, 3125, 3265, 3307
OFFSET
1,2
LINKS
FORMULA
Multiplicative closure of A006562.
PROG
(Haskell)
import Data.Set (singleton, fromList, union, deleteFindMin)
a225494 n = a225494_list !! (n-1)
a225494_list = 1 : h (singleton p) ps [p] where
(p:ps) = a006562_list
h s xs'@(x:xs) ys
| m > x = h (s `union` (fromList $ map (* x) (1 : ys))) xs ys
| otherwise = m : h (s' `union` (fromList $ map (* m) ys')) xs' ys'
where ys' = m : ys; (m, s') = deleteFindMin s
CROSSREFS
Cf. A225493 (strong), A225495 (weak), A225496 (non-balanced).
Sequence in context: A147184 A036133 A062671 * A139479 A078569 A044082
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, May 09 2013
STATUS
approved