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 A003110 M0393 #30 May 17 2019 16:26:50 %S A003110 0,2,2,108,2028,32870,1213110,46493784,2310521000,137466038346, %T A003110 9842687925450,832295357128500 %N A003110 a(n) = number of special odd permutations of 2*n+1. %C A003110 a(n) is the number of odd permutations, pi(0),...,pi(2*n), of 0,...,2*n such that pi(0) = 0 and p(k) = k + pi(k) (mod 2*n+1), k=0,...,2*n is also a permutation of 0,...,2*n. - _Sean A. Irvine_, Jan 31 2015 %D A003110 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A003110 D. H. Lehmer, <a href="http://dx.doi.org/10.1016/0022-314X(73)90056-5">Some properties of circulants</a>, J. Number Theory 5 (1973), 43-54. %Y A003110 Cf. A003109 (special even permutations), A003110 (total). %K A003110 nonn,more %O A003110 1,2 %A A003110 _N. J. A. Sloane_ %E A003110 Name clarified and offset corrected by _Sean A. Irvine_, Jan 31 2015 %E A003110 a(8)-a(9) from _Sean A. Irvine_, Jan 31 2015 %E A003110 a(10)-a(12) from _Vaclav Kotesovec_, May 17 2019 (using the terms of A003111 and A003112)