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 A244521 #12 Mar 01 2020 20:44:17 %S A244521 1,2,3,6,11,22,45,90,184,370,751,1516,3053,6172,12405,25042,50323, %T A244521 101424,203880,410296,824871,1658338,3333405,6696814,13457112, %U A244521 27021758,54278993,108952646,218765704,439001338,881134467 %N A244521 Number of pseudo-square parallelogram (psp) polyominoes by semiperimeter. %C A244521 Terms taken from p. 13 of the Brlek et al. reference. %H A244521 Srecko Brlek, Andrea Frosini, Simone Rinaldi, Laurent Vuillon, <a href="https://doi.org/10.37236/1041">Tilings by translation: enumeration by a rational language approach</a>, The Electronic Journal of Combinatorics, vol.13, (2006). %Y A244521 Cf. A245185. %K A244521 nonn,more %O A244521 2,2 %A A244521 _Joerg Arndt_, Jul 20 2014 %E A244521 a(29)-a(32) from _Andrew Howroyd_, Mar 01 2020