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 A046212 #15 Jul 02 2025 16:01:56 %S A046212 1,1,1,6,1,30,1,140,1,630,1,2772,1,12012,1,51480,1,218790,1,923780,1, %T A046212 3879876,1,16224936,1,67603900,1,280816200,1,1163381400,1,4808643120, %U A046212 1,19835652870,1,81676217700,1,335780006100,1,1378465288200,1 %N A046212 First numerator and then denominator of central elements of Leibniz's Harmonic Triangle. %D A046212 L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 83, Problem 25. %F A046212 a(2n+1) = A056040(2n+1) = A100071(2n+1). - _M. F. Hasler_, Jan 25 2012 %Y A046212 Cf. A003506. %Y A046212 Cf. A002457. %K A046212 nonn,easy %O A046212 1,4 %A A046212 _Mohammad K. Azarian_ %E A046212 More terms from _James Sellers_, Dec 13 1999