A320910 - OEIS

A320910

a(n)/2^n is the expected length of the longest palindromic subsequence of a length-n binary string.

2, 6, 20, 50, 128, 302, 708, 1612, 3624, 8048, 17704, 38604, 83660, 180118, 386096, 823540, 1750564

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OFFSET

1,1

COMMENTS

By subsequence we mean "not necessarily contiguous subsequence".

LINKS

Table of n, a(n) for n=1..17.

EXAMPLE

For n = 3, the binary strings are 000, 001, 010, 011, and their bitwise complements, with longest palindromic subsequence of length 3,2,3,2 respectively, so a(3) = 2*(3+2+3+2) = 20.

CROSSREFS

Sequence in context: A056820 A204422 A027558 * A066397 A060344 A363600

Adjacent sequences: A320907 A320908 A320909 * A320911 A320912 A320913

KEYWORD

nonn,more

AUTHOR

Jeffrey Shallit, Oct 23 2018

STATUS

approved