OFFSET
1,3
LINKS
Pierre CAMI, Table of n, a(n) for n = 1..10000
EXAMPLE
1*2*2^2-1=7 prime q 1*2*7^2-1=97 also prime so a(1)=1.
MATHEMATICA
a[n_] := For[k = 1, True, k++, p = Prime[n]; If[PrimeQ[q = k*2*p^2 - 1] && PrimeQ[k*2*q^2 - 1], Return[k]]]; Table[a[n], {n, 1, 66}] (* Jean-François Alcover, Apr 12 2013 *)
PROG
SCRIPT
DIM k
DIM i, 0
DIM q
DIMS t
OPENFILEOUT myf, a(n).txt
LABEL a
SET i, i+1
IF i>20000 THEN END
SET k, 0
LABEL b
SET k, k+1
SETS t, %d, %d, %d\,; k; i; p(i)
SET q, k*2*p(i)^2-1
PRP q, t
IF ISPRP THEN GOTO c
GOTO b
LABEL c
SET q, k*2*q^2-1
PRP q, t
IF ISPRP THEN WRITE myf, t
IF ISPRP THEN GOTO a
GOTO b
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Apr 08 2013
EXTENSIONS
Typo in name fixed by Zak Seidov, Apr 11 2013
STATUS
approved