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 A186342 #5 Mar 30 2012 18:57:18 %S A186342 1,3,5,7,8,10,12,13,15,17,18,20,22,24,25,27,29,30,32,34,36,37,39,41, %T A186342 42,44,46,48,49,51,53,54,56,58,59,61,63,65,66,68,70,71,73,75,77,78,80, %U A186342 82,83,85,87,88,90,92,94,95,97,99,100,102,104,106,107,109,111,112,114,116,118,119,121,123,124,126,128,129,131,133,135,136,138,140,141,143,145,147,148,150,152,153,155,157,158,160,162,164,165,167,169,170 %N A186342 Adjusted joint rank sequence of (f(i)) and (g(j)) with f(i) before g(j) when f(i)=g(j), where f and g are the pentagonal numbers and the octagonal numbers. Complement of A186343. %C A186342 See A186219 for a discussion of adjusted joint rank sequences. %e A186342 First, write %e A186342 1..5...12....22..35..... (pentagonal) %e A186342 1....8....21........40.. (octagonal) %e A186342 Then replace each number by its rank, where ties are settled by ranking the pentagonal number before the octagonal: %e A186342 a=(1,3,5,7,8,10,12,13,15,...)=A186342 %e A186342 b=(2,4,6,9,11,14,16,19,21,...)=A186343. %t A186342 (* adjusted joint ranking; general formula *) %t A186342 d=1/2; u=3/2; v=-1/2; w=0; x=3; y=-2; z=0; %t A186342 h[n_]:=-y+(4x(u*n^2+v*n+w-z-d)+y^2)^(1/2); %t A186342 a[n_]:=n+Floor[h[n]/(2x)]; %t A186342 k[n_]:=-v+(4u(x*n^2+y*n+z-w+d)+v^2)^(1/2); %t A186342 b[n_]:=n+Floor[k[n]/(2u)]; %t A186342 Table[a[n], {n, 1, 100}] (* A186342 *) %t A186342 Table[b[n], {n, 1, 100}] (* A186343 *) %Y A186342 Cf. A186219, A186343, A186344, A186345, %Y A186342 A000326 (pentagonal), A000567 (octagonal). %K A186342 nonn %O A186342 1,2 %A A186342 _Clark Kimberling_, Feb 18 2011