cp's OEIS Frontend

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.

A046912 Number of irreducible quasiorders with n labeled points.

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%I A046912 #16 Jul 09 2025 03:52:55
%S A046912 1,1,2,11,147,3412,121553,6353629,476850636,50811255045,7636459252135,
%T A046912 1610584897516674,474333338553730879,194055026319667963777,
%U A046912 109692570582311591696890,85221064877720762475072503,90542406571528792666541430863,130936936785995060562730057163556,256634185641525450158992588551158389
%N A046912 Number of irreducible quasiorders with n labeled points.
%H A046912 J. A. Wright, <a href="https://www.ams.org/journals/notices/197006/197006FullIssue.pdf">There are 718 6-point topologies, quasi-orderings and transgraphs</a>, Notices Amer. Math. Soc., 17 (1970), p. 646, Abstract #70T-A106.
%H A046912 J. A. Wright, <a href="/A000798/a000798_4.pdf">Letter to N. J. A. Sloane, Apr 06 1972, listing 18 sequences</a>
%F A046912 E.g.f.: A(x) = 2-1/B(x), where B(x) is e.g.f. of A000798. - _Vladeta Jovovic_, Jan 10 2006
%t A046912 A000798 = Cases[Import["https://oeis.org/A000798/b000798.txt", "Table"], {_, _}][[All, 2]]; lg = Length[A000798];
%t A046912 B[x_] = Sum[A000798[[n + 1]] x^n/n!, {n, 0, lg - 1}];
%t A046912 A[x_] = 2 - 1/B[x];
%t A046912 CoefficientList[A[x] + O[x]^lg, x]*Range[0, lg - 1]! (* _Jean-François Alcover_, Jan 01 2020 *)
%Y A046912 Cf. A046911.
%K A046912 nonn,more
%O A046912 0,3
%A A046912 John A. Wright
%E A046912 Corrected and extended by _Vladeta Jovovic_, Jan 10 2006
%E A046912 a(16)-a(18) from A000798 by _Jean-François Alcover_, Jan 01 2020