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 A093156 #8 Mar 07 2015 06:12:06 %S A093156 1,2,4,9,24,63,177,514,1527,4625,14230,44358,139779,444558,1425151, %T A093156 4600339,14939849,48778197,160019885,527200711,1743607826,5786756470, %U A093156 19266336882,64331275266,215377539119,722840378042,2431459847364 %N A093156 Another approximation to A000084(n). %C A093156 A more accurate version of A001573. %D A093156 J. Riordan and C. E. Shannon, The number of two-terminal series-parallel networks, J. Math. Phys., 21 (1942), 83-93. Reprinted in Claude Elwood Shannon: Collected Papers, edited by N. J. A. Sloane and A. D. Wyner, IEEE Press, NY, 1993, pp. 560-570. %F A093156 a(n) is the nearest integer to u(n) (with round(0.5)=0), where u(n) has o.g.f.: U(x) = (5 - 3*x - 2*x^2 - sqrt(9 - 30*x - 11*x^2 + 12*x^3 + 4*x^4))/2. [Riordan & Shannon] %Y A093156 Cf. A000084, A058585. %K A093156 nonn %O A093156 1,2 %A A093156 Pab Ter (pabrlos(AT)yahoo.com), May 11 2004