A069175 - OEIS

%I #15 Nov 02 2023 06:49:59

%S 211050,248640,253680,410340,507360,605640,1121190,1138830,1262100,

%T 2162580,2172870,2277660,4070220,6305460,7671510,11659410,12577110,

%U 14203770,14862120,17472840,18728640,18798360,20520570,21140700

%N Numbers k such that k-1, k+1, 2*k-1, 2*k+1, 4*k-1 and 4*k+1 are all prime.

%e 211050 is in the sequence because 211049, 211051, 422099, 422101, 844199 and 844201 are all prime.

%p isA069175 := proc(k)

%p     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

%p         true ;

%p     else

%p         false;

%p     end if;

%p end proc:

%p n := 1 :

%p for k from 4 by 2 do # create b-file

%p     if isA069175(k) then

%p         printf("%d %d\n",n,k) ;

%p         n := n+1 ;

%p     end if;

%p end do: # _R. J. Mathar_, Nov 02 2023

%t 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 *)

%Y Cf. A066388.

%K nonn

%O 1,1

%A _Don Reble_, Apr 09 2002

%E Offset changed to 1 by _Georg Fischer_, Sep 23 2022