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A103636
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Sum[d|n, d==0 mod 3, d^2].
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1
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0, 0, 9, 0, 0, 45, 0, 0, 90, 0, 0, 189, 0, 0, 234, 0, 0, 450, 0, 0, 450, 0, 0, 765, 0, 0, 819, 0, 0, 1170, 0, 0, 1098, 0, 0, 1890, 0, 0, 1530, 0, 0, 2250, 0, 0, 2340, 0, 0, 3069, 0, 0, 2610, 0, 0, 4095, 0, 0, 3258, 0, 0, 4914, 0, 0, 4500, 0, 0, 5490, 0, 0, 4770, 0, 0, 7650
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OFFSET
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1,3
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LINKS
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FORMULA
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MAPLE
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seq(op([0, 0, 9*numtheory:-sigma[2](k)]), k=1..50); # Robert Israel, Jan 11 2018
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MATHEMATICA
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Table[Total[Select[Divisors[n], Divisible[#, 3]&]^2], {n, 100}] (* Harvey P. Dale, May 07 2014 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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