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 A223935 Odd primes p(i) such that 6*p(i+j)^2-1 is also prime for j = 0..3. 1

%I #21 Apr 10 2013 12:13:17

%S 48497,48907,493747,578453,1223777,1249363,1933363,3304607,5160217,

%T 5765083,6022087,6205937,7740127,7757447,7862843,8173537,8938627,

%U 11989177,13789033,17649223,18142693,18829117,20006813,20601593,23938867,24448063,24478043

%N Odd primes p(i) such that 6*p(i+j)^2-1 is also prime for j = 0..3.

%H Pierre CAMI, <a href="/A223935/b223935.txt">Table of n, a(n) for n = 1..131</a>

%e p(4990)=48497 and 6*48497*48497-1=14111754053 is prime,

%e p(4991)=48523 and 6*48523*48523-1=14126889173 is prime,

%e p(4992)=48527 and 6*48527*48527-1=14129218373 is prime,

%e p(4993)=48533 and 6*48533*48533-1=14132712533 is prime,

%e so a(1)=p(4990)=48497

%t Reap[ For[ n=1; i=2, i < 5*10^6, i++, If[And @@ PrimeQ /@ Table[p[j] = Prime[i+j]; 6*p[j]^2-1, {j, 0, 3}], Print["i = ", i, " a(", n, ") = ", p[0]]; n++; Sow[ p[0] ] ] ] ][[2, 1]] (* _Jean-François Alcover_, Apr 09 2013 *)

%o PFGW and SCRIPTIFY

%o SCRIPT

%o DIM i,4000

%o DIMS t

%o OPENFILEOUT myf,res.txt

%o LABEL loop1

%o SET i,i+1

%o IF i==9999997 THEN END

%o SETS t,%d,%d\,;i;p(i)

%o PRP 6*p(i)*p(i)-1,t

%o IF ISPRP THEN GOTO a

%o GOTO loop1

%o LABEL a

%o SET i,i+1

%o SETS t,%d,%d\,;i;p(i)

%o PRP 6*p(i)*p(i)-1,t

%o IF ISPRP THEN GOTO b

%o GOTO loop1

%o LABEL b

%o SET i,i+1

%o SETS t,%d,%d\,;i;p(i)

%o PRP 6*p(i)*p(i)-1,t

%o IF ISPRP THEN GOTO c

%o GOTO loop1

%o LABEL c

%o SET i,i+1

%o SETS t,%d,%d\,;i;p(i)

%o PRP 6*p(i)*p(i)-1,t

%o IF ISPRP THEN WRITE myf,t

%o GOTO loop1

%K nonn

%O 1,1

%A _Pierre CAMI_, Mar 29 2013

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Last modified February 24 10:37 EST 2024. Contains 370294 sequences. (Running on oeis4.)