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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: A024380 A258331 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 April 18 06:48 EDT 2019. Contains 322209 sequences. (Running on oeis4.)