

A327240


3smooth numbers k such that k1 and (k2)/2 are prime.


3



6, 8, 12, 24, 48, 108, 384, 864, 8748, 995328, 2348273369088, 7421703487488, 21422803359744, 3470494144278528, 161919374795459002368, 1838129271989302091317248, 2168345519443636233418208968704, 28070062609828769223367060340342784
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OFFSET

1,1


COMMENTS

Numbers k of the form 2^a*3^b such that k1 and (k2)/2 are prime.
For all terms k except 6 and 8, k2 is in A325204.
All terms except 6 and 12 end in 4 or 8.


LINKS

Ray Chandler, Table of n, a(n) for n = 1..39 (terms < 10^1000)


EXAMPLE

a(3)=12 is a term because 12=2^2*3 and 11 and 10/2 are prime.


MATHEMATICA

nmax = 10^35;
Select[Sort[Flatten[Table[2^i*3^j, {j, 0, Log[3, nmax]}, {i, Log[2, nmax/3^j]}]]], PrimeQ[#  1] && PrimeQ[(#  2)/2] &]


CROSSREFS

Cf. A003586, A325204, A325255.
Sequence in context: A315873 A072057 A212351 * A274001 A324212 A160133
Adjacent sequences: A327237 A327238 A327239 * A327241 A327242 A327243


KEYWORD

nonn


AUTHOR

Ray Chandler, Sep 14 2019


STATUS

approved



