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 A134521 #11 Mar 26 2022 04:08:58 %S A134521 1,2,1,1,3,1,2,3,4,1,1,5,6,5,1,2,5,11,10,6,1,1,7,15,21,15,7,1,2,7,22, %T A134521 35,36,21,8,1,1,9,28,57,70,57,28,9,1,2,9,37,84,127,126,85,36,10,1,1, %U A134521 11,45,121,210,253,210,121,45,11,1,2,11,56,165,331,462,463,330,166,55,12,1 %N A134521 Triangle read by rows: T(n,k) = binomial(n,k) + (n + k) mod 2. %C A134521 Row sums = A134522: (1, 3, 5, 10, 18, 35, 67, ...). %C A134521 A007318 + A000012 - A128174 as infinite lower triangular matrices. %H A134521 Andrew Howroyd, <a href="/A134521/b134521.txt">Table of n, a(n) for n = 0..1274</a> %e A134521 First few rows of the triangle: %e A134521 1; %e A134521 2, 1; %e A134521 1, 3, 1; %e A134521 2, 3, 4, 1; %e A134521 1, 5, 6, 5, 1; %e A134521 2, 5, 11, 10, 6, 1; %e A134521 1, 7, 15, 21, 15, 7, 1; %e A134521 ... %o A134521 (PARI) T(n,k)=if(k<=n, binomial(n,k) + (n+k)%2, 0) \\ _Andrew Howroyd_, Aug 10 2018 %Y A134521 Row sums are A134522. %Y A134521 Cf. A128174, A000012. %K A134521 nonn,tabl %O A134521 0,2 %A A134521 _Gary W. Adamson_, Oct 29 2007 %E A134521 Name changed and a(39) corrected by _Andrew Howroyd_, Aug 10 2018