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A073118
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Total sum of prime parts in all partitions of n.
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10
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0, 2, 5, 9, 19, 33, 57, 87, 136, 206, 311, 446, 650, 914, 1284, 1762, 2432, 3276, 4433, 5888, 7824, 10272, 13479, 17471, 22642, 29087, 37283, 47453, 60306, 76112, 95931, 120201, 150338, 187141, 232507, 287591, 355143, 436849, 536347, 656282, 801647, 976095
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OFFSET
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1,2
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LINKS
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FORMULA
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G.f.: Sum_{i>=1} prime(i)*x^prime(i)/(1 - x^prime(i)) / Product_{j>=1} (1 - x^j). - Ilya Gutkovskiy, Feb 01 2017
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EXAMPLE
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For n = 6 we have:
--------------------------------------
. Sum of
Partitions prime parts
--------------------------------------
6 .......................... 0
3 + 3 ...................... 6
4 + 2 ...................... 2
2 + 2 + 2 .................. 6
5 + 1 ...................... 5
3 + 2 + 1 .................. 5
4 + 1 + 1 .................. 0
2 + 2 + 1 + 1 .............. 4
3 + 1 + 1 + 1 .............. 3
2 + 1 + 1 + 1 + 1 .......... 2
1 + 1 + 1 + 1 + 1 + 1 ...... 0
--------------------------------------
Total ..................... 33
So a(6) = 33. (End)
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MAPLE
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b:= proc(n, i) option remember; local h, j, t;
if n<0 then [0, 0]
elif n=0 then [1, 0]
elif i<1 then [0, 0]
else h:= [0, 0];
for j from 0 to iquo(n, i) do
t:= b(n-i*j, i-1);
h:= [h[1]+t[1], h[2]+t[2]+`if`(isprime(i), t[1]*i*j, 0)]
od; h
fi
end:
a:= n-> b(n, n)[2]:
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MATHEMATICA
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f[n_] := Apply[Plus, Select[ Flatten[ IntegerPartitions[n]], PrimeQ[ # ] & ]]; Table[ f[n], {n, 1, 41} ]
a[n_] := Sum[Total[FactorInteger[k][[All, 1]]]*PartitionsP[n-k], {k, 1, n}] - PartitionsP[n-1]; Array[a, 50] (* Jean-François Alcover, Dec 27 2015 *)
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PROG
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(PARI) a(n)={sum(k=1, n, vecsum(factor(k)[, 1])*numbpart(n-k))} \\ Andrew Howroyd, Dec 28 2017
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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