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A355199
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Sum of all the parts in the partitions of n into exactly 3 prime parts.
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3
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0, 0, 0, 0, 0, 0, 6, 7, 8, 18, 10, 22, 24, 26, 14, 45, 32, 68, 36, 57, 40, 105, 44, 115, 72, 125, 78, 189, 84, 203, 60, 186, 96, 297, 68, 280, 144, 333, 152, 390, 80, 451, 126, 430, 176, 540, 138, 611, 192, 588, 250, 765, 208, 848, 162, 770, 280, 969, 174, 944, 240, 976, 372
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OFFSET
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0,7
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LINKS
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FORMULA
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a(n) = n * Sum_{j=1..floor(n/3)} Sum_{i=j..floor((n-j)/2)} c(i) * c(j) * c(n-i-j), where c = A010051.
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EXAMPLE
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a(9) = 18; since 9 can be written as the sum of 3 primes in two ways: 2+2+5 = 3+3+3 and the sum of all the parts of these partitions is (2+2+5)+(3+3+3) = 18, we have a(9) = 18.
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MATHEMATICA
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Table[n*Sum[Sum[(PrimePi[i] - PrimePi[i - 1]) (PrimePi[j] - PrimePi[j - 1]) (PrimePi[n - i - j] - PrimePi[n - i - j - 1]), {i, j, Floor[(n - j)/2]}], {j, Floor[n/3]}], {n, 0, 80}]
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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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