A048664 - OEIS

A048664

Number of rooted 2-dimensional polyominoes with n square cells, with no symmetries removed.

1, 4, 18, 76, 315, 1296, 5320, 21800, 89190, 364460, 1487948, 6070332, 24750570, 100868236, 410919990, 1673486992, 6813529348, 27734769756, 112874034844, 459295593200, 1868653768443, 7601716598916, 30920563717052, 125759730486432, 511445050400275, 2079809585544808, 8457048866652588, 34386482811155244

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

REFERENCES

Dan Hoey, Bill Gosper and Richard C. Schroeppel, Discussions in Math-Fun Mailing list, circa Jul 13 1999.

LINKS

Jean-François Alcover, Table of n, a(n) for n = 1..56

R. C. Schroeppel, A few mathematical experiments, Experimental Mathematics Workshop, Oakland, 2004.

FORMULA

a(n) = n * A001168(n). - Andrew Howroyd, Dec 04 2018

MATHEMATICA

A001168 = Cases[Import["https://oeis.org/A001168/b001168.txt", "Table"], {_, _}][[All, 2]];