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A069175
Numbers k such that k-1, k+1, 2*k-1, 2*k+1, 4*k-1 and 4*k+1 are all prime.
2
211050, 248640, 253680, 410340, 507360, 605640, 1121190, 1138830, 1262100, 2162580, 2172870, 2277660, 4070220, 6305460, 7671510, 11659410, 12577110, 14203770, 14862120, 17472840, 18728640, 18798360, 20520570, 21140700
OFFSET
1,1
EXAMPLE
211050 is in the sequence because 211049, 211051, 422099, 422101, 844199 and 844201 are all prime.
MAPLE
isA069175 := proc(k)
if isprime(k-1) and isprime(k+1) and isprime(2*k-1) and isprime(2*k+1) and isprime(4*k-1) and isprime(4*k+1) then
true ;
else
false;
end if;
end proc:
n := 1 :
for k from 4 by 2 do # create b-file
if isA069175(k) then
printf("%d %d\n", n, k) ;
n := n+1 ;
end if;
end do: # R. J. Mathar, Nov 02 2023
MATHEMATICA
lst={}; Do[If[PrimeQ[n-1]&&PrimeQ[n+1]&&PrimeQ[2*n-1]&&PrimeQ[2*n+1]&&PrimeQ[4*n-1]&&PrimeQ[4*n+1], Print[n]; AppendTo[lst, n]], {n, 11!}]; lst (* Vladimir Joseph Stephan Orlovsky, Jan 05 2009 *)
CROSSREFS
Cf. A066388.
Sequence in context: A172825 A072760 A178421 * A340158 A097021 A236086
KEYWORD
nonn
AUTHOR
Don Reble, Apr 09 2002
EXTENSIONS
Offset changed to 1 by Georg Fischer, Sep 23 2022
STATUS
approved