This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A247706 #18 Feb 06 2017 18:33:46 %S A247706 1,1,0,3,0,2,16,20,20,0,135,204,140,16,6,944,1432,1164,296,170,0,4814, %T A247706 8796,8452,4068,1708,92,20,26435,58656,66994,41648,17494,2700,762,0, %U A247706 158761,410000,520728,371456,175810,46648,12876,440,62,978044,2783560,3836254,3107308,1696312,609772,172724,18220,3160,0 %N A247706 Number T(n,k) of tilings of a 5 X n rectangle with pentominoes of any shape and exactly k pentominoes of shape P; triangle T(n,k), n>=0, 0<=k<=n, read by rows. %C A247706 Sum_{k>0} k * T(n,k) = A247739(n). %H A247706 Alois P. Heinz, <a href="/A247706/b247706.txt">Rows n = 0..140, flattened</a> %H A247706 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentomino">Pentomino</a> %e A247706 T(2,2) = 2: %e A247706 .___. .___. %e A247706 | | | | %e A247706 | ._| |_. | %e A247706 |_| | | |_| %e A247706 | | | | %e A247706 |___| |___| . %e A247706 Triangle T(n,k) begins: %e A247706 00 : 1; %e A247706 01 : 1, 0; %e A247706 02 : 3, 0, 2; %e A247706 03 : 16, 20, 20, 0; %e A247706 04 : 135, 204, 140, 16, 6; %e A247706 05 : 944, 1432, 1164, 296, 170, 0; %e A247706 06 : 4814, 8796, 8452, 4068, 1708, 92, 20; %e A247706 07 : 26435, 58656, 66994, 41648, 17494, 2700, 762, 0; %e A247706 08 : 158761, 410000, 520728, 371456, 175810, 46648, 12876, 440, 62; %Y A247706 Row sums give A174249 or A233427(n,5). %Y A247706 Column k=0 gives A247770. %Y A247706 Even bisection of main diagonal gives A247076. %Y A247706 Cf. A247739. %K A247706 nonn,tabl %O A247706 0,4 %A A247706 _Alois P. Heinz_, Sep 22 2014