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A224491
Smallest k such that k*2*p(n)^2-1=q is prime k*2*q^2-1=r k*2*r^2-1=s, r and s are also prime.
8
705, 1, 306, 390, 2539, 526, 1939, 439, 7048, 286, 561, 985, 90, 2385, 2089, 328, 2266, 664, 4245, 2451, 453, 391, 411, 406, 4068, 4975, 8151, 199, 834, 4423, 169, 76, 5710, 861, 3930, 1659, 1246, 2838, 750, 153, 8664, 3730, 1195, 7815, 1746, 1735, 594, 985
OFFSET
1,1
MATHEMATICA
a[n_] := For[k = 1, True, k++, p = Prime[n]; If[PrimeQ[q = k*2*p^2 - 1] && PrimeQ[r = k*2*q^2 - 1] && PrimeQ[k*2*r^2 - 1], Return[k]]]; Table[a[n], {n, 1, 48}] (* Jean-François Alcover, Apr 12 2013 *)
PROG
(PFGW & SCRIPTIFY)
SCRIPT
DIM k
DIM i, 0
DIM q
DIMS t
OPENFILEOUT myf, a(n).txt
LABEL a
SET i, i+1
IF i>5600 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 GOTO d
GOTO b
LABEL d
SET q, k*2*q^2-1
PRP q, t
IF ISPRP THEN WRITE myf, t
IF ISPRP THEN GOTO e
GOTO b
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Apr 08 2013
EXTENSIONS
Typo in name fixed by Zak Seidov, Apr 11 2013
STATUS
approved