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 A002468 M2945 N1186 #58 Feb 16 2025 08:32:25
%S A002468 0,0,1,3,13,65,397,2819,22831,207605,2094121,23205383,280224451,
%T A002468 3662810249,51523391965,776082247979,12463259986087,212573743211549,
%U A002468 3837628837381201,73108996989052175,1465703611456618891,30847249002794047793,679998362512214208901,15668677914172813691699,376683592679293811722735
%N A002468 The game of Mousetrap with n cards: the number of permutations of n cards having at least one hit after 2.
%C A002468 The subsequence of primes begins: 3, 13, 397, 2819, no more through a(19). - _Jonathan Vos Post_, Feb 01 2011
%D A002468 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.
%D A002468 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D A002468 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A002468 Joerg Arndt, <a href="/A002468/b002468.txt">Table of n, a(n) for n = 1..102</a>
%H A002468 R. K. Guy and R. J. Nowakowski, <a href="/A002467/a002467_1.pdf">Mousetrap</a>, Preprint, Feb 10 1993 [Annotated scanned copy]
%H A002468 J. Metzger, <a href="/A002467/a002467_3.pdf">Email to N. J. A. Sloane, Apr 30 1991</a>
%H A002468 Daniel J. Mundfrom, <a href="http://dx.doi.org/10.1006/eujc.1994.1057">A problem in permutations: the game of 'Mousetrap'</a>. European J. Combin. 15 (1994), no. 6, 555-560.
%H A002468 A. Steen, <a href="http://resolver.sub.uni-goettingen.de/purl?PPN600494829_0015/DMDLOG_0031">Some formulas respecting the game of mousetrap</a>, Quart. J. Pure Applied Math., 15 (1878), 230-241.
%H A002468 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Mousetrap.html">Mousetrap</a>
%F A002468 a(n) = A001563(n) - A002469(n+2). (corrected by _Sean A. Irvine_ and _Joerg Arndt_, Feb 10 2014)
%t A002468 a[n_] := (n-2)*(n-2)!-(n-4)*Subfactorial[n-3]-(n-3)*Subfactorial[n-2]; a[1]=a[2]=0; a[3]=1; Table[a[n], {n, 1, 21}] (* _Jean-François Alcover_, Dec 12 2014 *)
%Y A002468 Cf. A002467, A002468, A002469, A028306, etc.
%K A002468 nonn,easy,nice
%O A002468 1,4
%A A002468 _N. J. A. Sloane_
%E A002468 Added two more terms, _Joerg Arndt_, Feb 15 2014