A174393 - OEIS

%I #8 Feb 03 2019 01:53:56

%S 1,2,4,7,106,388,930,2999,3127,3974,4982,5154,6350,6612,6750,7661,

%T 7693,8783,10156,10465,11989,13101,13266,15349,15351,17476,18087,

%U 19305,20670,21434,22671,23134,23613,23667,24493,24509,25780,27474,28764,30457

%N Numbers k such that 6*prime(k) -+ {1,5} are all prime.

%e a(1)=1 because

%e   prime(1)*6 - 5 =  7,

%e   prime(1)*6 - 1 = 11,

%e   prime(1)*6 + 1 = 13, and

%e   prime(1)*6 + 5 = 17

%e are all prime.

%p isA174393 := proc(n) local p ; p := ithprime(n) ; isprime(p*6-1) and isprime(p*6-5) and isprime(p*6+1) and isprime(p*6+5); end proc: for n from 1 to 40000 do if isA174393(n) then printf("%d,",n) ; end if; end do: # _R. J. Mathar_, Mar 29 2010

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Mar 18 2010

%E Corrected and extended by _Charles R Greathouse IV_, Mar 18 2010