Every fourth term of the sequence of natural numbers 1,2,3,4,... is halved.
1, 2, 3, 2, 5, 6, 7, 4, 9, 10, 11, 6, 13, 14, 15, 8, 17, 18, 19, 10, 21, 22, 23, 12, 25, 26
1 seqfan posts
Fri Mar 11 13:57:44 CET 2011 [seqfan] Re: Period lengths of k^2 mod n not in OEIS ?