A080947 Numbers having more than three divisors that are also suffixes in binary representation.

63, 126, 231, 252, 255, 363, 399, 462, 495, 504, 510, 567, 627, 726, 735, 759, 798, 845, 891, 903, 924, 975, 990, 1008, 1020, 1023, 1071, 1134, 1215, 1239, 1254, 1365, 1407, 1419, 1452, 1455, 1470, 1518, 1575, 1596, 1690, 1695, 1743, 1755, 1782, 1806, 1848

Offset: 1

Author

Reinhard Zumkeller, Feb 25 2003

Keywords

• nonn
• base

Comments

A080942(a(n))>3.

Examples

			a(4) = 252: divisors(252) = {1, 2, 3, 4->'100', 6, 7, 9, 12->'1100', 14, 18, 21, 28->'11100', 36, 42, 63, 84, 126, 252->'11111100'}: A080946(252) = #{4, 12, 28, 252} = 4;
a(15) = 735: divisors(735) = {1->'1', 3->'11', 5, 7->'111', 15->'1111', 21, 35, 49, 105, 147, 245, 735->'1011011111'}: A080942(735) = #{1, 3, 7, 15, 735} = 5.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A080946, A007088, A080940, A080941.

Programs

Haskell

a080947 n = a080947_list !! (n-1)
a080947_list = filter ((> 3) . a080942) [1..]
-- Reinhard Zumkeller, Mar 27 2014