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A169963
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Number of (2n+1)-digit squares in carryless arithmetic mod 10.
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3
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5, 46, 452, 4504, 45008, 450016, 4500032, 45000064, 450000128, 4500000256, 45000000512, 450000001024, 4500000002048, 45000000004096, 450000000008192, 4500000000016384, 45000000000032768, 450000000000065536, 4500000000000131072, 45000000000000262144
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OFFSET
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0,1
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LINKS
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FORMULA
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For formula see Maple code.
a(n) = 12*a(n-1)-20*a(n-2). G.f.: -(14*x-5) / ((2*x-1)*(10*x-1)). - Colin Barker, May 11 2013
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MAPLE
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f :- n->2^((n-1)/2) + add( 5^d*2^((n+1)/2), d=0..(n-3)/2) + 2^((n+3)/2)*5^((n-1)/2);
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CROSSREFS
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See A059729 for the actual squares.
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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