A224493 Smallest k such that k*2*p(n)^2+1 is prime.

2, 1, 2, 2, 3, 2, 6, 15, 12, 6, 8, 2, 5, 6, 2, 14, 3, 23, 2, 5, 2, 3, 5, 3, 6, 11, 2, 9, 3, 5, 6, 3, 14, 8, 5, 6, 2, 2, 5, 9, 8, 11, 3, 2, 11, 3, 6, 5, 6, 5, 2, 5, 3, 8, 15, 14, 3, 5, 20, 5, 6, 14, 14, 8, 5, 2, 8, 2, 6, 18, 14, 3, 6, 9, 5, 12, 3, 9, 15, 18, 6, 6, 3

Offset

1,1

Links

Pierre CAMI, Table of n, a(n) for n = 1..10000

Mathematica

a[n_] := For[k = 1, True, k++, p = Prime[n]; If[PrimeQ[k*2*p^2 + 1], Return[k]]]; Table[ a[n] , {n, 1, 83}] (* Jean-François Alcover, Apr 12 2013 *)
sk[n_]:=Module[{k=1}, While[!PrimeQ[2*k*n^2+1], k++]; k]; Table[sk[n], {n, Prime[ Range[ 90]]}] (* Harvey P. Dale, Sep 22 2019 *)

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>10000 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 WRITE myf, t
IF ISPRP THEN GOTO a
GOTO b

Crossrefs

Cf. A224489, A224490, A224491, A224492, A224494, A224495, A224496.

Sequence in context: A029169 A202090 A241760 * A129193 A262446 A205147

Adjacent sequences: A224490 A224491 A224492 * A224494 A224495 A224496

Keyword

nonn

Author

Pierre CAMI, Apr 08 2013

Status

approved