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A281824 Numbers that are the sum of 6 consecutive semiprimes. 2

%I #11 Dec 08 2017 18:28:34

%S 58,75,91,107,123,142,161,175,191,205,225,241,258,278,297,316,332,348,

%T 366,385,405,429,452,473,491,508,524,536,546,566,590,614,639,664,690,

%U 706,718,732,747,762,782,802,822,838,851,872,889,906,924,945,968,990

%N Numbers that are the sum of 6 consecutive semiprimes.

%C Semiprime analog of A127333. First terms that are also in A127333: 690, 990, 1172, 1250, 1286, 2288, 4798, 5064.

%H Charles R Greathouse IV, <a href="/A281824/b281824.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) ~ 6n log n/log log n. - _Charles R Greathouse IV_, Jan 31 2017

%t Total /@ Partition[Select[Range[4, 200], 2 == PrimeOmega[#] &], 6, 1]

%o (PARI) do(n)=my(v=List([58]),u=List(),t=58); forprime(p=2,n\2, forprime(q=2,min(p,n\p), listput(u,p*q))); u=Set(u); for(i=7,#u, listput(v, t+=u[i]-u[i-6])); Set(v) \\ _Charles R Greathouse IV_, Jan 31 2017

%Y Cf. A001358, A127333.

%K nonn

%O 1,1

%A _Zak Seidov_, Jan 31 2017

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Last modified July 22 18:05 EDT 2024. Contains 374540 sequences. (Running on oeis4.)