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A280830
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Number of partitions of n into two products-of-three-primes.
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1
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 2, 0, 2, 1, 2, 0, 1, 0, 0, 1, 1, 1, 2, 0, 2, 0, 1, 1, 2, 1, 2, 2, 2, 0, 3, 0, 3, 1, 2, 1, 0, 0, 1, 1, 3, 2, 4, 1, 2, 2, 1, 1, 3, 1, 3, 1, 2, 2, 3, 0, 4, 2, 4, 1, 4
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OFFSET
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1,36
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LINKS
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FORMULA
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EXAMPLE
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a(36) = 2; there are 2 partitions of 36 into two products-of-three-primes: (28,8) and (18,18).
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MAPLE
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with(numtheory): A280830:=n->add(floor(bigomega(i)/3)*floor(3/bigomega(i))*floor(3/bigomega(n-i))*floor(bigomega(n-i)/3), i=2..floor(n/2)): seq(A280830(n), n=1..100);
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MATHEMATICA
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Table[Sum[Floor[PrimeOmega[i]/3] Floor[3/PrimeOmega[i]] Floor[3/PrimeOmega[n - i]] Floor[PrimeOmega[n - i]/3], {i, 2, Floor[n/2]}], {n, 1, 90}] (* Indranil Ghosh, Mar 09 2017, translated from Maple code *)
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PROG
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(PARI) for(n=1, 90, print1(sum(i=2, floor(n/2), floor(bigomega(i)/3) * floor(3/bigomega(i)) * floor(3/bigomega(n - i)) * floor(bigomega(n - i)/3)), ", ")) \\ Indranil Ghosh, Mar 09 2017
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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