login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Primes in A168472.
1

%I #10 Mar 21 2019 04:36:51

%S 181,293,907,2311,2971,3547,4019,4523,5651,7103,7753,8419,14489,15443,

%T 17417,18097,18443,22171,31123,32063,41611,42683,44851,48761,67829,

%U 69221,79273,98047,103903,107347,114407,122597,132967,149909,154081

%N Primes in A168472.

%H Robert Israel, <a href="/A168473/b168473.txt">Table of n, a(n) for n = 1..10000</a>

%p N:= 10^4: # to get all a(n) where A006881(n) < N

%p Primes:= select(isprime, [2, seq(2*k+1, k=1..floor(N/2))]):

%p L:= sort(convert({seq(seq(p*q, q=Primes[1..ListTools:-BinaryPlace(Primes, N/p)]), p=Primes)} minus {seq(p^2, p=Primes)}, list)):

%p A168472:= ListTools:-PartialSums(L):

%p select(isprime, A168472); # _Robert Israel_, Mar 20 2019

%t f[n_]:=Last/@FactorInteger[n]=={1,1}; s=0;lst={};Do[If[f[n],If[PrimeQ[s+=n],AppendTo[lst,s]]],{n,7!}];lst

%t With[{nn=50},Select[Accumulate[Union[Times@@@Subsets[Prime[Range[2nn]],{2}]]],PrimeQ,nn]] (* _Harvey P. Dale_, Aug 08 2013 *)

%Y Cf. A168472.

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Nov 26 2009