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 A283106 #10 Mar 06 2017 17:34:43 %S A283106 1,1,1,2,2,4,5,7,9,11,12,16,18,22,26,30,33,37,41,47,52,58,62,69,74,80, %T A283106 86,92,97,106,112,120,127,135,143,152,159,168,176,186,193,205,213,225, %U A283106 235,246,256,269,281,291,302 %N A283106 Number of distinct envelope areas of the polyominoes of order n. %C A283106 The envelope of a polyomino is the minimal rectangle containing it. %e A283106 a(3) = 2; %e A283106 The two possible envelopes are %e A283106 |*| %e A283106 |*| %e A283106 |*| area = 3; %e A283106 and %e A283106 |*| | %e A283106 |*|*| area = 4. %Y A283106 Cf. A071764 (distinct envelope ratios). %K A283106 nonn %O A283106 0,4 %A A283106 _Francois Alcover_, Feb 28 2017