OFFSET
0,13
COMMENTS
Considered as a triangle, T(n,k) is the number of polyominoes of n cells having a (cell) perimeter of k.
LINKS
Sean A. Irvine, Table of n, a(n) for n = 0..437; rows 0..19 flattened
Sean A. Irvine, Java program (github)
FORMULA
A001168(n) = Sum_{k=0..2*n+2} T(n,k).
EXAMPLE
Polynomials begin:
1;
x^4;
2*x^6;
4*x^7 + 2*x^8;
9*x^8 + 8*x^9 + 2*x^10;
...
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Sean A. Irvine, Oct 16 2020
STATUS
approved