OFFSET
1,2
COMMENTS
a(n) is the number of free polyominoes that have both width and height <= n. Compare this to Craig Knecht's A268311 which has both height and width = n. The word "aligned" in the title refers to the restriction that the polyominoes have edges parallel to the sides of the square, in contrast with A268427.
FORMULA
a(n) = Sum_{i=1..n*(n+1)/2} A268371(i). - John Mason, Sep 11 2024
CROSSREFS
KEYWORD
nonn,more
AUTHOR
John Mason, Feb 04 2016
EXTENSIONS
a(6) from Talmon Silver, Jul 29 2020
a(7) from John Mason, Sep 11 2024
STATUS
approved