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The number of n-digit numbers requiring 4 nonzero squares in their representation as sum of squares.
3

%I #12 May 25 2024 16:44:33

%S 1,14,150,1500,14999,150000,1499999,15000000,149999998,1500000001,

%T 14999999999,149999999999,1500000000001,14999999999999,

%U 149999999999999,1500000000000001,14999999999999998,149999999999999999,1500000000000000003,14999999999999999996

%N The number of n-digit numbers requiring 4 nonzero squares in their representation as sum of squares.

%C A049415(n) + A180426(n) + A180429(n) + a(n) = A052268(n).

%H Eric W. Weisstein: <a href="http://mathworld.wolfram.com/LagrangesFour-SquareTheorem.html"> MathWorld : Lagrange's Four-Square Theorem.</a>

%H Eric W. Weisstein: <a href="http://mathworld.wolfram.com/SumofSquaresFunction.html">MathWorld: Sum of Squares Function.</a>

%F a(n) = A167615(n)-A167615(n-1).

%Y Cf. A004215, A167615.

%Y Cf. A049415, A052268, A180426, A180429.

%K nonn,base

%O 1,2

%A _Martin Renner_, Jan 18 2011