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 A093412 #10 Oct 21 2019 02:12:08 %S A093412 1,2,1,3,5,1,4,7,3,1,5,3,2,7,1,6,11,5,9,4,1,7,13,3,11,5,9,1,8,5,7,13, %T A093412 2,11,5,1,9,17,4,3,7,13,3,11,1,10,19,9,17,8,15,7,13,6,1,11,7,5,19,3, %U A093412 17,2,5,7,13,1,12,23,11,21,10,19,9,17,8,15,7,1,13,25,6,23,11,3,5,19,9,17,4 %N A093412 Triangle read by rows: a(n, k) is the numerator of (n + (n-1) + ... + (n-k+1))/(1 + 2 + ... + k), 0 < k <= n. %C A093412 A093415 gives the corresponding denominators. %F A093412 a(n, k) = (2n+1-k)/gcd(2n+1-k, k+1). %e A093412 Triangle a(n,k) (with rows n >= 1 and columns k >= 1) begins as follows: %e A093412 1; %e A093412 2, 1; %e A093412 3, 5, 1; %e A093412 4, 7, 3, 1; %e A093412 5, 3, 2, 7, 1; %e A093412 6, 11, 5, 9, 4, 1; %e A093412 7, 13, 3, 11, 5, 9, 1; %e A093412 8, 5, 7, 13, 2, 11, 5, 1; %e A093412 9, 17, 4, 3, 7, 13, 3, 11, 1; %e A093412 ... - _Petros Hadjicostas_, Oct 20 2019 %Y A093412 Cf. A093413, A093414, A093415. %K A093412 easy,nonn,tabl,frac %O A093412 1,2 %A A093412 _Amarnath Murthy_, Mar 30 2004 %E A093412 Edited and extended by _David Wasserman_, Feb 01 2006