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 A153860 #13 May 07 2025 08:18:27 %S A153860 1,0,1,1,1,1,-1,0,1,1,1,0,0,1,1,-1,0,0,0,1,1,1,0,0,0,0,1,1,-1,0,0,0,0, %T A153860 0,1,1,1,0,0,0,0,0,0,1,1,-1,0,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,1,1 %N A153860 Triangle by columns: leftmost column = (1, 0, 1, -1, 1, -1, 1, ...); columns >1 = (1, 1, 0, 0, 0, ...). %C A153860 As an infinite lower triangular matrix M; M * [1,2,3,...] = A063210: (1, 2, 6, 6, 10, 10, 14, 14, ...). %C A153860 M * [1, 3, 5, 7, ...] = A047471, {1,3} mod 8. %C A153860 Eigensequence of the triangle = A066983 starting (1, 1, 3, 3, 7, 9, 17, 25, ...). %C A153860 Binomial transform of the triangle = A153861. %C A153860 Row sums = A153284: (1, 1, 3, 1, 3, 1, 3, 1, ...). %H A153860 Reinhard Zumkeller, <a href="/A153860/b153860.txt">Rows n = 1..100 of triangle, flattened</a> %F A153860 Triangle by columns: leftmost column = (1, 0, 1, -1, 1, ...); columns > 1 = (1, 1, 0, 0, 0, ...). %e A153860 First few rows of the triangle: %e A153860 1; %e A153860 0, 1; %e A153860 1, 1, 1; %e A153860 -1, 0, 1, 1; %e A153860 1, 0, 0, 1, 1; %e A153860 -1, 0, 0, 0, 1, 1; %e A153860 1, 0, 0, 0, 0, 1, 1; %e A153860 -1, 0, 0, 0, 0, 0, 1, 1; %e A153860 1, 0, 0, 0, 0, 0, 0, 1, 1; %e A153860 ... %o A153860 (Haskell) %o A153860 a153860 n k = a153860_tabl !! (n-1) !! (k-1) %o A153860 a153860_row n = a153860_tabl !! (n-1) %o A153860 a153860_tabl = [1] : [0, 1] : iterate (\(x:xs) -> -x : 0 : xs) [1, 1, 1] %o A153860 -- _Reinhard Zumkeller_, Dec 16 2013 %Y A153860 Cf. A153861 (binomial transform), A153284 (row sums), A063210, A047471, A066983. %K A153860 tabl,sign %O A153860 1,1 %A A153860 _Gary W. Adamson_, Jan 03 2009