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A168472
Partial sums of products of two distinct primes (A006881).
13
6, 16, 30, 45, 66, 88, 114, 147, 181, 216, 254, 293, 339, 390, 445, 502, 560, 622, 687, 756, 830, 907, 989, 1074, 1160, 1247, 1338, 1431, 1525, 1620, 1726, 1837, 1952, 2070, 2189, 2311, 2434, 2563, 2696, 2830, 2971, 3113, 3256, 3401, 3547, 3702, 3860, 4019
OFFSET
1,1
LINKS
MAPLE
N:= 1001: # to get all a(n) where A006881(n) < N
Primes:= select(isprime, [2, seq(2*k+1, k=1..floor(N/2))]):
L:= sort(convert({seq(seq(p*q, q=Primes[1..ListTools:-BinaryPlace(Primes, N/p)]), p=Primes)} minus {seq(p^2, p=Primes)}, list)):
ListTools:-PartialSums(L); # Robert Israel, Apr 29 2018
MATHEMATICA
f[n_]:=Last/@FactorInteger[n]=={1, 1}; s=0; lst={}; Do[If[f[n], AppendTo[lst, s+=n]], {n, 6!}]; lst
With[{nn=50}, Take[Accumulate[Union[Times@@@Subsets[Prime[Range[nn]], {2}]]], nn]] (* Harvey P. Dale, Aug 08 2013 *)
CROSSREFS
Sequence in context: A164052 A264938 A350011 * A054000 A113742 A102214
KEYWORD
nonn
AUTHOR
STATUS
approved