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 A370714 #7 Feb 28 2024 17:59:35 %S A370714 1,6,78,780,8790,90708,1015692,10964760,122893926,1370476932, %T A370714 15518261220,176063641512,2014426860540,23109736996680, %U A370714 266397931733208,3079014279154224,35695144493030022,414708043501061988,4828444403991450612,56314242827277224712,657855733949279381652 %N A370714 a(n) = 4^n * [x^n] Product_{k>=1} 1/(1 - 3*x^k)^(1/2). %F A370714 G.f.: Product_{k>=1} 1/(1 - 3*(4*x)^k)^(1/2). %F A370714 a(n) ~ 12^n / sqrt(Pi*QPochhammer(1/3)*n). %t A370714 nmax = 25; CoefficientList[Series[Product[1/(1-3*x^k), {k, 1, nmax}]^(1/2), {x, 0, nmax}], x] * 4^Range[0, nmax] %t A370714 nmax = 25; CoefficientList[Series[Product[1/(1-3*(4*x)^k), {k, 1, nmax}]^(1/2), {x, 0, nmax}], x] %t A370714 nmax = 25; CoefficientList[Series[Sqrt[-2/QPochhammer[3,x]], {x, 0, nmax}], x] * 4^Range[0, nmax] %Y A370714 Cf. A242587, A370711. %K A370714 nonn %O A370714 0,2 %A A370714 _Vaclav Kotesovec_, Feb 27 2024