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%I #18 Oct 22 2023 16:53:51
%S 0,1,1,1,1,1,2,3,3,2,4,10,11,10,4,10,35,57,57,35,10,26,133,290,364,
%T 290,133,26
%N Triangle T(n,k) giving number of immersions of the oriented circle into the oriented plane with n double points and index k, k = -n-1, -n+1, ..., n-1, n+1.
%D V. I. Arnold, Topological Invariants of Plane Curves and Caustics, American Math. Soc., 1994, p. 18.
%H S. V. Duzhin, <a href="https://www.pdmi.ras.ru/~arnsem/dataprog/">Computer programs and data files of the participants of Arnold's seminar</a>, 1998-2010.
%H S. M. Gusein-Zade and F. S. Duzhin, <a href="https://doi.org/10.4213/rm48">On the number of topological types of plane curves</a>; (Russian) Uspekhi Mat. Nauk 53 (1998), no. 3(321), 197-198. <a href="https://doi.org/10.1070/rm1998v053n03abeh000048">English translation</a>: Russian Mathematical Surveys 53 (1998) 626-627.
%F T(n, n+1) = A003239(n). [Arnold, p. 12] - _Andrey Zabolotskiy_, Oct 22 2023
%Y Cf. A008980 (row sums), A008981, A008982, A008983, A054993, A008984 (k = n-1), A003239 (k = n+1).
%K nonn,nice,tabl,more
%O -1,7
%A _N. J. A. Sloane_
%E Name clarified and initial row added by _Andrey Zabolotskiy_, Oct 22 2023
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