cp's OEIS Frontend

A013582 Number of positions in game "Connect Four" (played on usual 6-row, 7-column board) after n moves, up to reflection.

%I A013582 #39 Feb 16 2025 08:32:32
%S A013582 1,4,25,121,568,2144,8231,27473,92244,279241,831581,2284733,6118941,
%T A013582 15465573,37720667,88273017,197300906,429114775,881951878,1784140720,
%U A013582 3373100313,6336692489,11005448210,19131647821,30415473928,48633111249
%N A013582 Number of positions in game "Connect Four" (played on usual 6-row, 7-column board) after n moves, up to reflection.
%H A013582 Sean A. Irvine, <a href="/A013582/b013582.txt">Table of n, a(n) for n = 0..42</a> [a(42) corrected by Sidney Cadot]
%H A013582 John Tromp, <a href="http://tromp.github.io/c4/c4.html">John's Connect Four Playground</a>, viewed Jan 23 2014.
%H A013582 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Connect-Four.html">Connect-Four</a>
%Y A013582 Cf. A212693.
%K A013582 nonn,fini,full
%O A013582 0,2
%A A013582 _Russ Cox_
%E A013582 Name clarified by _Charles R Greathouse IV_, Dec 01 2013
%E A013582 a(3)-a(13) corrected by _Sean A. Irvine_, Aug 09 2018. The corrected values were confirmed by _Russ Cox_ and extended through a(15), Aug 13 2018
%E A013582 a(16)-a(17) from _Sean A. Irvine_, Aug 15 2018
%E A013582 Remaining terms a(18)-a(42) from _Sean A. Irvine_, Oct 02 2018
%E A013582 a(42) corrected by _Sidney Cadot_, Dec 04 2022, after comparing results of an independent solver and confirming with _Sean A. Irvine_ that the previously given value was indeed erroneous.