A373755 - OEIS

%I #8 Jun 17 2024 07:56:39

%S 1,1,1,1,3,7,31,109,623,2951,20641,123216,1019051,7349140,70148989,

%T 593513485,6421463423,62382094567,754405836811,8277393686747,

%U 110644077164479,1353422057172923,19814920352425441,267391099520321166,4255291684449288503,62800765220575811118

%N a(n) = A205497(n, floor((n - 1) / 2)). The middle coefficients of the Eulerian zig-zag polynomials.

%H T. Kyle Petersen and Yan Zhuang, <a href="https://arxiv.org/abs/2403.07181">Zig-zag Eulerian polynomials</a>, arXiv:2403.07181 [math.CO], 2024.

%p 1, 1, 1, seq(A205497row(n)[iquo(n, 2)], n = 3..25);

%Y Cf. A205497, A373754.

%K nonn

%O 0,5

%A _Peter Luschny_, Jun 16 2024