A273008 a(n)/(4^(n-1)*(4^n - 1)) is the variance of the length of a longest common subsequence between two random binary strings of the length n.

1, 23, 476, 9463, 179708, 3285359, 58821148, 1036541808, 18048642524, 311226939840, 5325007685376, 90541291530096, 1531388084625152

Offset

1,2

Comments

A027433(n)/4^n gives the expected value of the length of a longest common subsequence between two random binary strings of the length n, and a(n)/(4^(n-1)*(4^n - 1)) gives the variance (the squared standard deviation) of that length.

Links

Table of n, a(n) for n=1..13.

Vacláv Chvátal, David Sankoff, Longest Common Subsequences of Two Random Sequences, Journal of Applied Probability, Vol. 12, No. 2 (Jun., 1975), pp. 306-315, DOI: 10.2307/3212444.

Wikipedia, Chvátal-Sankoff constants.

Crossrefs

Cf. A027433.

Sequence in context: A134733 A328348 A095256 * A015678 A293083 A014905

Adjacent sequences: A273005 A273006 A273007 * A273009 A273010 A273011

Keyword

nonn,hard,more

Author

Vladimir Reshetnikov, May 13 2016

Status

approved