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A224905
Smallest k such that (10^n+k, 10^n+k+2) and (10^(n+1)+k, 10^(n+1)+k+2) are two pairs of twin primes.
1
1, 49, 91, 1117, 2929, 721, 1819, 37237, 30979, 30967, 29629, 6457, 53269, 27727, 271159, 556651, 190489, 62797, 105259, 784777, 290659, 1320829, 438037, 1019317, 333991, 248371, 226609, 671227, 384571, 1573537, 366841, 954391, 1701247, 540811, 1105291
OFFSET
1,2
LINKS
EXAMPLE
10^1+1=11 prime as 13 10^2+1=101 prime as 103 so a(1)=1.
MATHEMATICA
sk[n_]:=Module[{k=1}, While[!AllTrue[{10^n+k, 10^n+k+2, 10^(n+1)+k, 10^(n+1)+k+2}, PrimeQ], k++]; k]; Array[sk, 35] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 09 2020 *)
PROG
PFGW & SCRIPTIFY
SCRIPT
DIM n, 0
DIM k, -1
DIMS t
OPENFILEOUT myf, a(n).txt
LABEL a
SET n, n+1
SET k, -1
LABEL b
SET k, k+2
SETS t, %d, %d\,; n; k
PRP 10^n+k, t
IF ISPRP THEN GOTO c
GOTO b
LABEL c
PRP 10^n+k+2, t
IF ISPRP THEN GOTO d
GOTO b
LABEL d
PRP 10^(n+1)+k, t
IF ISPRP THEN GOTO e
GOTO b
LABEL e
PRP 10^(n+1)+k+2, t
IF ISPRP THEN GOTO f
GOTO b
LABEL f
WRITE myf, t
SET k, k+2
GOTO a
CROSSREFS
Sequence in context: A084632 A020176 A146064 * A224846 A260469 A275419
KEYWORD
nonn
AUTHOR
Pierre CAMI, Jul 25 2013
STATUS
approved