A002976 - OEIS

%I M0034 #30 May 30 2026 16:39:44

%S 0,1,0,2,0,5,9,21,42,76,174,396,888,2023,4345,9921,22566,52436,121330,

%T 280300,652577,1526588,3593881,8499891,20122183,47851464,114106883,

%U 272918157,655503331,1575651737,3804038107,9190693494,22282629123,54116568153,131689795621,321266555821,784607412699

%N Number of certain self-avoiding walks with n steps on square lattice (see reference for precise definition).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H W. A. Beyer, <a href="/A005208/a005208.pdf">Letter to N. J. A. Sloane, 1980</a>

%H W. A. Beyer and M. B. Wells, <a href="https://doi.org/10.1016/0097-3165(72)90024-6">Lower bound for the connective constant of a self-avoiding walk on a square lattice</a>, J. Combin. Theory, A 13 (1972), 176-182.

%H Bert Dobbelaere, <a href="/A002976/a002976.cpp.txt">C++ program</a>

%F a(n) = A006142(n) + 2*A006143(n) + A006144(n). - _R. J. Mathar_, Oct 22 2007

%Y Cf. A001411, A037245.

%K nonn,walk

%O 4,4

%A _N. J. A. Sloane_

%E a(21)-a(40) from _Bert Dobbelaere_, May 08 2026