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 A232005 #6 Nov 19 2013 12:37:09 %S A232005 1,2,8,48,386,3781,49475,762869,13554897,266817541 %N A232005 Number of distinct resistances that can be produced from a circuit of resistors with resistances 1, 2, ..., n using only series and parallel combinations. %C A232005 Found by exhaustive search: all configurations of resistors were enumerated, resistances calculated, sorted, and distinct values counted. %C A232005 This sequence allows any circuits to be combined in series or in parallel (akin A000084); A051045 requires circuits to be combined with a single resistor at a time. %C A232005 This sequence regards circuits as distinct only if their resistance is different; A006351 regards circuits distinct if their configuration is different, although some may have the same resistance. %C A232005 This sequence considers resistors with contiguous resistances 1, 2, ..., n; A005840 considers arbitrarily different resistors, while A048211 considers n equal resistances. %e A232005 a(2) = 2 since given a 1-ohm and a 2-ohm resistor, a series circuit yields 3 ohms, while a parallel circuit yields 2/3 ohms, which thus yields two distinct resistances. %Y A232005 Cf. A005840, A006352, A048211, A051045. %K A232005 nonn,more %O A232005 1,2 %A A232005 _Dave R.M. Langers_, Nov 16 2013