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 A001830 M4439 N1877 #37 May 19 2024 08:40:40
%S A001830 1,7,61,661,8953,152917,3334921,94354981,3528929353,177999003157,
%T A001830 12340001650921,1194005625114661,162936187792764073,
%U A001830 31536761103831315157,8677703806537883683081,3395880602480076153665701,1889190751946097573211698313
%N A001830 Related to graded partially ordered sets.
%C A001830 Corresponds to the numbers c(7,n) in the Klarner paper. - _Sean A. Irvine_, Sep 24 2015
%D A001830 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D A001830 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A001830 John Cerkan, <a href="/A001830/b001830.txt">Table of n, a(n) for n = 0..112</a>
%H A001830 D. A. Klarner, <a href="https://doi.org/10.1016/S0021-9800(69)80100-6">The number of graded partially ordered sets</a>, J. Combin. Theory, 6 (1969), 12-19.
%H A001830 D. A. Klarner, <a href="/A000798/a000798_11.pdf">The number of graded partially ordered sets</a>, J. Combin. Theory, 6 (1969), 12-19. [Annotated scanned copy]
%H A001830 <a href="/index/Pos#posets">Index entries for sequences related to posets</a>
%F A001830 a(n) = Sum_{p+q+r+s+t+u+v=n} (n!/p!q!r!s!t!u!v!) 2^(pq+qr+rs+st+tu+uv) where (p,q,r,s,t,u,v) is any nonnegative composition of n. - _Sean A. Irvine_, Sep 24 2015
%Y A001830 Column k=7 of A361950.
%Y A001830 Cf. A000684, A001827, A001828, A001829, A047863.
%K A001830 nonn
%O A001830 0,2
%A A001830 _N. J. A. Sloane_
%E A001830 More terms from _Sean A. Irvine_, Sep 24 2015