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
KEYWORD
nonn,base
AUTHOR
Roger Cuculière, Oct 03 2012
EXTENSIONS
More terms from Alois P. Heinz, Oct 03 2012
STATUS
approved