Re:The On-Line Encyclopedia of Integer Sequences
by madcaptenor on Tuesday July 21, 2015 @09:47AM
(#9922195)
A000012 is the all-ones sequence: https://oeis.org/A000012. It even has a subreddit: https://www.reddit.com/r/A000012/
a(n) is also the number of permutations simultaneously avoiding 213, 231 and 321 in the classical sense which can be realized as labels on an increasing strict binary tree with 2n-1 nodes. See A245904 for more information on increasing strict binary trees. - Manda Riehl
Number of n-digit numbers the binary expansion of which contains one run of 1's. - Vladimir Shevelev