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 A131817 #11 Aug 21 2021 15:51:55 %S A131817 1,2,2,4,2,3,8,4,2,4,16,8,4,2,5,32,16,8,4,2,6,64,32,16,8,4,2,7,128,64, %T A131817 32,16,8,4,2,8,256,128,64,32,16,8,4,2,9,512,256,128,64,32,16,8,4,2,10, %U A131817 1024,512,256,128,64,32,16,8,4,2,11,2048,1024,512,256,128,64,32,16,8,4,2,12 %N A131817 a(n) = A051340(n) + A130321(n) - A000012(n). %H A131817 Michael De Vlieger, <a href="/A131817/b131817.txt">Table of n, a(n) for n = 0..11475</a> (rows 0 <= n <= 150, flattened) %F A131817 A051340 + A130321 - A000012 as infinite lower triangular matrices. %e A131817 First few rows of the triangle: %e A131817 1; %e A131817 2, 2; %e A131817 4, 2, 3; %e A131817 8, 4, 2, 4; %e A131817 16, 8, 4, 2, 5; %e A131817 32, 16, 8, 4, 2, 6; %e A131817 64, 32, 16, 8, 4, 2, 7; %e A131817 ... %t A131817 Array[Append[ConstantArray[1, # - 1], #] + 2^Range[# - 1, 0, -1] - 1 &, 12] // Flatten (* _Michael De Vlieger_, Aug 19 2021 *) %Y A131817 Cf. A051340, A083706 (row sums), A130321. %K A131817 nonn,tabl %O A131817 0,2 %A A131817 _Gary W. Adamson_, Jul 18 2007 %E A131817 More terms from _Jinyuan Wang_, Aug 19 2021