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 A028306 #13 Nov 05 2016 14:48:11 %S A028306 1,0,0,1,0,1,2,1,1,2,9,5,5,3,9,44,31,25,20,16,44,265,203,167,142,117, %T A028306 96,265,1854,1501,1267,1075,932,791,675,1854,14833,12449,10745,9311, %U A028306 8241,7132,6205,5413,14833,133496,114955,101005,88993,78607,70340,62141 %N A028306 Triangle read by rows of numbers of permutations eliminating just card k out of n in game of Mousetrap. %D A028306 R. K. Guy, Unsolved Problems Number Theory, E37. %D A028306 R. K. Guy and R. J. Nowakowski, "Mousetrap," in D. Miklos, V. T. Sos and T. Szonyi, eds., Combinatorics, Paul Erdős is Eighty. Bolyai Society Math. Studies, Vol. 1, pp. 193-206, 1993. %H A028306 R. K. Guy and R. J. Nowakowski, <a href="/A002467/a002467_1.pdf">Mousetrap</a>, Preprint, Feb 10 1993 [Annotated scanned copy] %Y A028306 Diagonals include A000166, A002469. Cf. A028305. %K A028306 tabl,nonn %O A028306 0,7 %A A028306 _N. J. A. Sloane_