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A025398
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Numbers that are the sum of 3 positive cubes in 3 or more ways.
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13
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5104, 9729, 12104, 12221, 12384, 13896, 14175, 17604, 17928, 19034, 20691, 21412, 21888, 24480, 28792, 29457, 30528, 31221, 32850, 34497, 35216, 36288, 38259, 39339, 39376, 40041, 40060, 40097, 40832, 40851, 41033, 41040, 41364, 41966, 42056, 42687
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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a(1) = A230477(3) = 5104 = 1^3 + 12^3 + 15^3 = 2^3 + 10^3 + 16^3 = 9^3 + 10^3 + 15^3. - Jonathan Sondow, Oct 24 2013
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MATHEMATICA
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Select[ Range[ 50000], 2 < Length @ Cases[ PowersRepresentations[#, 3, 3], {_?Positive, _?Positive, _?Positive}] &] (* adapted from Alcover's program for A008917 by Jonathan Sondow, Oct 24 2013 *)
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PROG
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(PARI) is(n)=k=ceil((n-2)^(1/3)); d=0; for(a=1, k, for(b=a, k, for(c=b, k, if(a^3+b^3+c^3==n, d++)))); d
n=3; while(n<50000, if(is(n)>=3, print1(n, ", ")); n++) \\ Derek Orr, Aug 27 2015
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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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