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A154729 Products of three distinct primes of the form 6*n + 1 (see A002476). 6

%I

%S 1729,2821,3367,3913,4123,4921,5551,5719,6097,6643,7189,7657,8029,

%T 8113,8827,8911,9139,9331,9373,9709,9919,10507,10621,11137,11557,

%U 12649,12901,13237,13699,13741,14287,14497,14539,14833,14911,15067,15799,15841

%N Products of three distinct primes of the form 6*n + 1 (see A002476).

%C Note that a(1) = 1729 is the Hardy-Ramanujan number (see taxicab numbers in A001235, A011541).

%C Equivalently, products of three distinct primes of the form 3*n + 1. - _Omar E. Pol_, Feb 17 2018

%H G. L. Honaker, Jr. and Chris Caldwell, <a href="https://primes.utm.edu/curios/page.php?number_id=94&amp;submitter=Pol">Prime Curios!</a>, Number 1729.

%e The first three primes of the form 6*n + 1 are 7, 13 and 19, so a(1) = 7*13*19 = 1729. - _Omar E. Pol_, Feb 17 2018

%t Module[{nn=40,prs},prs=Select[6*Range[nn]+1,PrimeQ];Take[Times@@@ Subsets[ prs,{3}]//Union,nn]] (* _Harvey P. Dale_, Feb 17 2018 *)

%Y Cf. A001235, A002476, A011541, A154716, A154717, A154728.

%K nonn

%O 1,1

%A _Omar E. Pol_, Jan 18 2009

%E a(5)-a(38) from _Donovan Johnson_, Jan 28 2009

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Last modified August 23 22:20 EDT 2019. Contains 326254 sequences. (Running on oeis4.)