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 A136561 #12 May 31 2017 07:57:52 %S A136561 1,2,3,4,6,9,-5,-1,5,14,13,8,7,12,26,-30,-17,-9,-2,10,36,75,45,28,19, %T A136561 17,27,63,-200,-125,-80,-52,-33,-16,11,74,524,324,199,119,67,34,18,29, %U A136561 103,-1299,-775,-451,-252,-133,-66,-32,-14,15,118 %N A136561 Triangle read by rows: n-th diagonal (from the right) is the sequence of (signed) differences between pairs of consecutive terms in the (n-1)th diagonal. The rightmost diagonal (A136562) is defined: A136562(1)=1; A136562(n) is the smallest integer > A136562(n-1) such that any (signed) integer occurs at most once in the triangle A136561. %C A136561 Requiring that the absolute values of the differences in the difference triangle only occur at most once each leads to the Zorach additive triangle. (See A035312.) %e A136561 The triangle begins: %e A136561 1, %e A136561 2,3, %e A136561 4,6,9, %e A136561 -5,-1,5,14, %e A136561 13,8,7,12,26, %e A136561 -30,-17,-9,-2,10,36. %e A136561 Example: %e A136561 Considering the rightmost value of the 4th row: Writing a 10 here instead, the first 4 rows of the triangle become: %e A136561 1 %e A136561 2,3 %e A136561 4,6,9 %e A136561 -9,-5,1,10 %e A136561 But 1 already occurs earlier in the triangle. So 10 is not the rightmost element of row 4. %e A136561 Checking 11,12,13,14; 14 is the smallest value that can be the rightmost element of row 4 and not have any elements of row 4 occur earlier in the triangle. %Y A136561 Cf. A035312, A136562, A136563. %K A136561 sign,tabl %O A136561 1,2 %A A136561 _Leroy Quet_, Jan 06 2008 %E A136561 Rows 7-10 from _Andrey Zabolotskiy_, May 29 2017