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%I #28 Feb 15 2020 11:03:31
%S 1,2,5,13,39,124,403,1304,4301,14370,47575,157153,512311,1663977,
%T 5446573
%N a(n) is the number of distinct valid solutions taking into account the ambiguity of open and closed absolute value bars for an input of -1 to -2*(n)-1 with absolute value bars between each (|-1|, |-1|-2|-3|, |-1|-2|-3|-4|-5|, etc.).
%C a(5) is the solution to Jim Propp's submitted problem published in FiveThirtyEight's "The Riddler" column.
%H FiveThirtyEight, <a href="https://fivethirtyeight.com/features/how-many-more-palindrome-dates-will-you-see/">Problem origin</a>
%H Twitter, <a href="https://twitter.com/JimPropp/status/1224177172362989571?ref_src=twsrc%5Etfw">Initial Observation</a>
%e For n = 2 (input of |-1|-2|-3|-4|-5|) the solutions are 5 and -5, so a(2) = 2.
%K nonn,more
%O 1,2
%A _Tyler Barron_, Feb 12 2020
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