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 A057753 #29 Jan 15 2023 17:35:46 %S A057753 1,2,10,27,150,641,3796,21525,134863,846159,5464173,35548106, %T A057753 234007149,1551388944,10361158723 %N A057753 Total area of all polyominoes with perimeter 2n. %H A057753 Andrew Clarke, <a href="http://www.recmath.com/PolyPages/PolyPages/Isopolyos.html">Isoperimetrical Polyominoes</a> %H A057753 Andrew Clarke, <a href="/A057730/a057730.gif">Picture from Andrew Clarke's page showing the polyominoes of perimeters 4, 6, 8 and 10.</a> %e A057753 a(2*n=4) = 1 with area 1: 1*1=1. %e A057753 a(2*n=6) is 1 with area 2: 1*2=2. %e A057753 a(2*n=8) is 2 with area 3, 1 with area 4: 2*3+4=10. %e A057753 a(2*n=10) is 4 with area 4, 1 with area 5, 1 with area 6: 4*4+5+6=27. %e A057753 a(2*n=12) = 11*5 +7*6 +4*7 +2*8 +1*9 = 150. %e A057753 a(2*n=14) = 27*6 +21*7 +21*8+ 9*9 + 6*10 +1*11 + 1*12 = 641. - _R. J. Mathar_, Feb 18 2021 %e A057753 a(2*n=16) = 7*83 + 8*91 + 9*89 + 10*67 + 11*45 + 12*23 + 13*11 + 14*4 + 15*2 + 16*1. - _John Mason_, Feb 18 2021 %Y A057753 Cf. A057730. %K A057753 nonn,more %O A057753 2,2 %A A057753 _N. J. A. Sloane_, Nov 04 2000 %E A057753 Link updated by _William Rex Marshall_, Dec 16 2009 %E A057753 Offset set to 2 by _R. J. Mathar_, Feb 18 2021 %E A057753 a(8) from _John Mason_, Feb 18 2021 %E A057753 a(9)-a(16) from _John Mason_, Sep 08 2022