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A164521 Primes of the form A162142(k) - 2. 1
3373, 753569, 2146687, 3048623, 6539201, 8120599, 10218311, 17373977, 18609623, 19034161, 32461757, 44738873, 59776469, 69426529, 72511711, 77854481, 88121123, 116930167, 133432829, 299418307, 338608871, 413493623, 458314009, 679151437 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Primes p such that p+2 is the cube of a squarefree semiprime, i.e., such that p+2 = q^3*r^3 where q and r are two distinct primes.
LINKS
EXAMPLE
3373 + 2 = 3375 = 3^3*5^3. 753569 + 1 = 753571 = 7^3*13^3.
MAPLE
N:= 10^10: # to get all terms <= N
P:= select(isprime, [seq(i, i=3..floor((N+2)^(1/3)/3))]):
R:= NULL:
for i from 1 to nops(P) do
for j from 1 to i-1 do
p:= (P[i]*P[j])^3-2;
if p > N then break fi;
if isprime(p) then R:= R, p fi
od od:
sort([R]); # Robert Israel, Jun 05 2018
MATHEMATICA
f3[n_]:=FactorInteger[n][[1, 2]]==3&&Length[FactorInteger[n]]==2&&FactorInteger[n][[2, 2]]==3; lst={}; Do[p=Prime[n]; If[f3[p+2], AppendTo[lst, p]], {n, 4, 4*9!}]; lst
csfsQ[n_]:=Module[{c=Surd[n+2, 3]}, SquareFreeQ[c]&&PrimeOmega[c]==2]; Select[Prime[Range[353*10^5]], csfsQ] (* Harvey P. Dale, Jan 07 2018 *)
CROSSREFS
Sequence in context: A117921 A052357 A218908 * A251153 A305500 A250568
KEYWORD
nonn
AUTHOR
EXTENSIONS
Edited and examples corrected by R. J. Mathar, Aug 21 2009
STATUS
approved

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Last modified March 28 08:02 EDT 2024. Contains 371236 sequences. (Running on oeis4.)