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 A371357 #8 Mar 31 2024 15:19:13 %S A371357 1,2,12,40,560,2016,14784,54912,1647360,6223360,47297536,180590592, %T A371357 2769055744,10650214400,82158796800,317680680960,19696202219520, %U A371357 76467608616960,594748067020800,2316387208396800,36135640450990080,141101072237199360,1103153837490831360 %N A371357 a(n) = 2^(n - HammingWeight(n)) * binomial(2*n, n). %H A371357 Paolo Xausa, <a href="/A371357/b371357.txt">Table of n, a(n) for n = 0..1000</a> %F A371357 a(n) = A060818(n) * A000984(n). %p A371357 HammingWeight := n -> add(convert(n, base, 2)): %p A371357 a := n -> 2^(n - HammingWeight(n))*binomial(2*n, n): %p A371357 seq(a(n), n = 0..22); %t A371357 Array[2^(# - DigitCount[#, 2, 1]) * Binomial[2*#, #] &, 25, 0] (* _Paolo Xausa_, Mar 31 2024 *) %Y A371357 Cf. A060818, A000984. %K A371357 nonn %O A371357 0,2 %A A371357 _Peter Luschny_, Mar 23 2024