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Vampire numbers (definition 1) in binary: n has a nontrivial factorization using n's bits.
3

%I #25 Jan 27 2017 13:25:53

%S 159,175,287,303,315,318,319,343,350,351,375,567,574,575,591,603,606,

%T 623,627,630,636,638,679,686,687,699,700,702,735,750,763,765,1127,

%U 1134,1135,1148,1150,1167,1179,1182,1183,1203,1206,1212,1215,1239,1243,1246,1247,1251,1254,1260,1271,1272

%N Vampire numbers (definition 1) in binary: n has a nontrivial factorization using n's bits.

%C Nontrivial means that there must be at least two factors.

%H Ely Golden, <a href="/A280967/b280967.txt">Table of n, a(n) for n = 1..10000</a>

%H Ely Golden, <a href="/A280967/a280967_2.sagews.txt">General program for generating vampire number sequences</a>

%e 175 is a member as 175 = 7 * 25 = 10101111_2 = 111_2 * 11001_2

%e 5887 is a member as 5887 = 7 * 29 * 29 = 1011011111111_2 = 111_2 * 11101_2 * 11101_2

%Y Cf. A020342

%K nonn,base

%O 1,1

%A _Ely Golden_, Jan 11 2017