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 A278645 #16 Dec 07 2016 11:08:44 %S A278645 1,1,2,3,5,7,8,15,22,29,23,45,74,103,132,68,142,245,377,509,641,210, %T A278645 455,832,1341,1982,2623,3264,665,1497,2838,4820,7443,10707,13971, %U A278645 17235,2162,5000,9820,17263,27970,41941,59176,76411,93646,7162,16982,34245,62215,104156,163332,239743,333389,427035,520681 %N A278645 Triangle read by rows in which each new term is the sum of its two largest neighbors in the structure. %C A278645 To evaluate T(n,k) consider only the two largest neighbors of T(n,k) that are present in the triangle when T(n,k) should be a new term in the triangle. %C A278645 For the same idea but for a square spiral see A278180; and for a hexagonal spiral see A278619. %C A278645 It appears that the same idea for an isosceles triangle and also for a square array gives A030237. %e A278645 Triangle begins: %e A278645 1; %e A278645 1, 2; %e A278645 3, 5, 7; %e A278645 8, 15, 22, 29; %e A278645 23, 45, 74, 103, 132; %e A278645 68, 142, 245, 377, 509, 641; %e A278645 210, 455, 832, 1341, 1982, 2623, 3264; %e A278645 665, 1497, 2838, 4820, 7443, 10707, 13971, 17235; %e A278645 2162, 5000, 9820, 17263, 27970, 41941, 59176, 76411, 93646; %e A278645 7162, 16982, 34245, 62215, 104156, 163332, 239743, 333389, 427035, 520681; %e A278645 ... %Y A278645 Cf. A030237, A278180, A278317, A278619. %K A278645 nonn,tabl %O A278645 1,3 %A A278645 _Omar E. Pol_, Nov 24 2016