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 A217446 #11 Oct 10 2012 17:11:26 %S A217446 1,585,331668,213208980,156226437720,129158041750920, %T A217446 119164964083502400,121503028361696976960,135757575541042424323200, %U A217446 165013333307050666667644800,216831999996550400000012812800,306342399999513113600000180544000,463124479999926454528000002723302400 %N A217446 Sum of the squares of numbers obtained by digit permutations of the concatenation of first n numbers. %H A217446 Alois P. Heinz, <a href="/A217446/b217446.txt">Table of n, a(n) for n = 1..100</a> %F A217446 a(n) = (1/12)*(n+1)!*(n*R'(n)+(3*n+2)*R(n)^2) with R(n) = (10^n-1)/9 and R'(n) = (10^(2*n)-1)/99. %e A217446 a(1) = 1^2 = 1. %e A217446 a(2) = 12^2 + 21^2 = 585. %e A217446 a(3) = 123^2 + 132^2 + 213^2 + 231^2 + 312^2 + 321^2 = 331668. %p A217446 R:= n-> (10^n-1)/9: RP:= n-> (10^(2*n)-1)/99: %p A217446 a:= n-> (1/12)*(n+1)!*(n*RP(n)+(3*n+2)*R(n)^2): %p A217446 seq (a(n), n=1..15); # _Alois P. Heinz_, Oct 03 2012 %Y A217446 Cf. A071268. %K A217446 nonn,base %O A217446 1,2 %A A217446 _Roger Cuculière_, Oct 03 2012 %E A217446 More terms from _Alois P. Heinz_, Oct 03 2012