Integers whose aliquot sequences terminate by encountering the prime 3. Also known as the prime family 3.
3, 4, 9, 12, 15, 16, 26, 30, 33, 42, 45, 46, 52, 54, 66, 72, 78, 86, 87, 90, 102, 105, 114
1 seqfan posts
Sat Feb 20 14:40:11 CET 2010 [seqfan] Re: Mystery tour with a(n)=sigma(a(n-1))