OFFSET
0,2
COMMENTS
A polyomino of shape I is a rectangle of width 1.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..200
Wikipedia, Polyomino
FORMULA
G.f.: (1 - 153*x + 6777*x^2 - 132415*x^3 + 1336362*x^4 - 7606262*x^5 + 25527903*x^6 - 51325185*x^7 + 61507605*x^8 - 42648785*x^9 + 16029360*x^10 - 2890728*x^11 + 181440*x^12)/(1 - 185*x + 10404*x^2 - 259107*x^3 + 3361183*x^4 - 24886632*x^5 + 110360811*x^6 - 299572675*x^7 + 499926324*x^8 - 508443601*x^9 + 305734685*x^10 - 101727600*x^11 + 16409736*x^12 - 907200*x^13). - Andrew Howroyd, Dec 23 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jan 30 2015
STATUS
approved