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 A262616 #27 Feb 13 2017 16:23:16 %S A262616 1,4,1,16,4,1,64,16,4,1,256,64,16,4,1,1024,256,64,16,4,1,4096,1024, %T A262616 256,64,16,4,1,16384,4096,1024,256,64,16,4,1,65536,16384,4096,1024, %U A262616 256,64,16,4,1,262144,65536,16384,4096,1024,256,64,16,4,1,1048576,262144,65536,16384,4096,1024,256,64,16,4,1 %N A262616 Triangle read by rows: T(n,k) = 4^(n-k), n>=0, 0<=k<=n. %C A262616 A triangle of the same family of A130321 and A140303, with the same offset. %C A262616 T(n,k) is also the number of hidden crosses of size k+1 formed by squares and rectangles in the toothpick structure of A139250 after 2^(n+2) stages. The last term in every row represents the central cross of the toothpick structure. %H A262616 Indranil Ghosh, <a href="/A262616/b262616.txt">Rows 0..100, flattened</a> %H A262616 N. J. A. Sloane, <a href="/wiki/Catalog_of_Toothpick_and_CA_Sequences_in_OEIS">Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a> %F A262616 T(n,k) = A000302(n-k). %e A262616 Triangle begins: %e A262616 1; %e A262616 4, 1; %e A262616 16, 4, 1; %e A262616 64, 16, 4, 1; %e A262616 256, 64, 16, 4, 1; %e A262616 1024, 256, 64, 16, 4, 1; %e A262616 4096, 1024, 256, 64, 16, 4, 1; %e A262616 16384, 4096, 1024, 256, 64, 16, 4, 1; %e A262616 65536, 16384, 4096, 1024, 256, 64, 16, 4, 1; %e A262616 262144, 65536, 16384, 4096, 1024, 256, 64, 16, 4, 1; %e A262616 1048576, 262144, 65536, 16384, 4096, 1024, 256, 64, 16, 4, 1; %e A262616 4194304, 1048576, 262144, 65536, 16384, 4096, 1024, 256, 64, 16, 4, 1; %e A262616 ... %t A262616 Table[4^(n - k), {n, 0, 10}, {k, 0, n}] // Flatten (* _Michael De Vlieger_, Jul 17 2016 *) %Y A262616 Column k gives A000302. %Y A262616 Row sums give the positive terms of A002450. %Y A262616 Alternating row sums give the positive terms of A015521. %Y A262616 Cf. A130321, A139250, A140303, A152571, A152716. %K A262616 nonn,tabl,easy %O A262616 0,2 %A A262616 _Omar E. Pol_, Nov 23 2015