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A085252 Number of ways to write n as sum of two powerful numbers (A001694). 6


%S 0,1,0,0,1,0,0,1,1,1,0,1,1,0,0,1,2,1,0,1,0,0,0,1,1,1,0,1,1,0,1,1,2,1,

%T 1,2,1,0,0,2,2,0,1,1,1,0,0,1,0,2,0,2,1,1,0,0,2,1,1,0,1,0,1,1,2,0,0,2,

%U 0,0,0,2,2,1,0,2,0,0,0,2,2,1,0,0,2,0,0,1,2,1,1,0,0,0,0,1,2,1,1,1,1,0

%N Number of ways to write n as sum of two powerful numbers (A001694).

%C a(A085253(n))=0; a(A076871(n))>0; a(A085254(n))=1; a(A085255(n))>1.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PowerfulNumber.html">Powerful Number</a>

%e a(81)=2: 81 = 9+72=A001694(4)+A001694(12) =

%e 32+49=A001694(8)+A001694(10).

%K nonn

%O 1,17

%A _Reinhard Zumkeller_, Jun 23 2003

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Last modified February 28 00:28 EST 2020. Contains 332319 sequences. (Running on oeis4.)