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 A217446 Sum of the squares of numbers obtained by digit permutations of the concatenation of first n numbers. 1
 1, 585, 331668, 213208980, 156226437720, 129158041750920, 119164964083502400, 121503028361696976960, 135757575541042424323200, 165013333307050666667644800, 216831999996550400000012812800, 306342399999513113600000180544000, 463124479999926454528000002723302400 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Alois P. Heinz, Table of n, a(n) for n = 1..100 FORMULA 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. EXAMPLE a(1) = 1^2 = 1. a(2) = 12^2 + 21^2 = 585. a(3) = 123^2 + 132^2 + 213^2 + 231^2 + 312^2 + 321^2 = 331668. MAPLE R:= n-> (10^n-1)/9: RP:= n-> (10^(2*n)-1)/99: a:= n-> (1/12)*(n+1)!*(n*RP(n)+(3*n+2)*R(n)^2): seq (a(n), n=1..15); # Alois P. Heinz, Oct 03 2012 CROSSREFS Cf. A071268. Sequence in context: A258331 A352979 A022243 * A171436 A020362 A051988 Adjacent sequences: A217443 A217444 A217445 * A217447 A217448 A217449 KEYWORD nonn,base AUTHOR Roger Cuculière, Oct 03 2012 EXTENSIONS More terms from Alois P. Heinz, Oct 03 2012 STATUS approved

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Last modified December 9 09:12 EST 2023. Contains 367690 sequences. (Running on oeis4.)