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 A140685 #29 Jan 03 2024 09:31:29 %S A140685 1,2,2,2,1,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2, %T A140685 2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2, %U A140685 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2 %N A140685 Triangle T(n,k) read by rows: T(n,k) = 1 if n is odd and k=(n-1)/2; T(n,k) = 2 otherwise. %C A140685 Row sums give A042948. %H A140685 Antti Karttunen, <a href="/A140685/b140685.txt">Table of n, a(n) for n = 1..10440; the first 144 rows of the triangle</a> %e A140685 The triangle starts in row n=1 with columns 0 <= k < n as: %e A140685 1; %e A140685 2, 2; %e A140685 2, 1, 2; %e A140685 2, 2, 2, 2; %e A140685 2, 2, 1, 2, 2; %e A140685 2, 2, 2, 2, 2, 2; %e A140685 2, 2, 2, 1, 2, 2, 2; %e A140685 2, 2, 2, 2, 2, 2, 2, 2; %e A140685 2, 2, 2, 2, 1, 2, 2, 2, 2; %e A140685 2, 2, 2, 2, 2, 2, 2, 2, 2, 2; %o A140685 (Scheme) %o A140685 (define (A140685 n) (A140685tr (A002024 n) (- (A002260 n) 1))) %o A140685 (define (A140685tr n k) (if (and (odd? n) (= k (/ (- n 1) 2))) 1 2)) %Y A140685 Cf. A002024, A002260, A104041. %K A140685 nonn,tabl,easy %O A140685 1,2 %A A140685 _Roger L. Bagula_ and _Mats Granvik_, Jul 11 2008 %E A140685 Definition simplified by the Assoc. Eds. of the OEIS, Oct 12 2010 %E A140685 More terms from _Antti Karttunen_, Oct 10 2017