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Partial sums of A000798.
0

%I #10 Dec 30 2019 10:27:20

%S 1,2,6,35,390,7332,216859,9752100,652531454,63912820877,9040966693920,

%T 1825887005430112,521181458071204133,208402575114740157174,

%U 115825454552169007964634,88852094573138413500449755,93499965506283177978710943850,134231450058844163850300579669696,261626767193693218968916427480786899

%N Partial sums of A000798.

%C Number of different quasi-orders (or topologies, or transitive digraphs) with n labeled elements.

%C The subsequence of primes in this partial sum begins: 2, 216859.

%F a(n) = Sum_{i=0..n} A000798(i).

%t Cases[Import["https://oeis.org/A000798/b000798.txt", "Table"], {_, _}][[All, 2]] // Accumulate (* _Jean-François Alcover_, Dec 30 2019 *)

%Y Cf. A000798, A001035 (labeled posets), A001930 (unlabeled topologies), A000112 (unlabeled posets), A006057.

%K nonn

%O 0,2

%A _Jonathan Vos Post_, Feb 17 2010

%E Missing term 7332 added and extended by _Jean-François Alcover_, Dec 30 2019