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 A247702 #25 Feb 06 2017 18:40:36 %S A247702 1,1,5,52,4,437,60,4,3342,584,80,21734,5372,818,24,2,155685,49540, %T A247702 8800,620,44,1153475,439780,92500,10140,856,28,2,8422634,3726836, %U A247702 914142,127596,13338,760,48,60853524,30683256,8544440,1425320,176156,14404,1078,32,2 %N A247702 Number T(n,k) of tilings of a 5 X n rectangle with pentominoes of any shape and exactly k pentominoes of shape F; triangle T(n,k), n>=0, 0<=k<=max(delta_{3,n},floor((n-2)/2)*2), read by rows. %C A247702 Sum_{k>0} k * T(n,k) = A247735(n). %H A247702 Alois P. Heinz, <a href="/A247702/b247702.txt">Rows n = 0..150, flattened</a> %H A247702 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentomino">Pentomino</a> %e A247702 T(3,1) = 4: %e A247702 ._____. ._____. ._____. ._____. %e A247702 |_. | | ._| | ._. | | ._. | %e A247702 | |___| |___| | |_| |_| |_| |_| %e A247702 |_. ._| |_. ._| | .___| |___. | %e A247702 | |_| | | |_| | |_| | | |_| %e A247702 |_____| |_____| |_____| |_____| . %e A247702 Triangle T(n,k) begins: %e A247702 00 : 1; %e A247702 01 : 1; %e A247702 02 : 5; %e A247702 03 : 52, 4; %e A247702 04 : 437, 60, 4; %e A247702 05 : 3342, 584, 80; %e A247702 06 : 21734, 5372, 818, 24, 2; %e A247702 07 : 155685, 49540, 8800, 620, 44; %e A247702 08 : 1153475, 439780, 92500, 10140, 856, 28, 2; %e A247702 09 : 8422634, 3726836, 914142, 127596, 13338, 760, 48; %e A247702 10 : 60853524, 30683256, 8544440, 1425320, 176156, 14404, 1078, 32, 2; %Y A247702 Row sums give A174249 or A233427(n,5). %Y A247702 Column k=0 gives A247766. %Y A247702 Cf. A247735. %K A247702 nonn,tabf %O A247702 0,3 %A A247702 _Alois P. Heinz_, Sep 22 2014