OFFSET
1,3
COMMENTS
Conjecture: There is always one such k if n>1.
LINKS
Pierre CAMI, Table of n, a(n) for n = 1..501
MATHEMATICA
sktp[n_]:=Module[{k=1, c=5^n}, While[AnyTrue[c(c-k)+{1, -1}, CompositeQ], k++]; k]; Join[{0}, Array[ sktp, 60, 2]] (* Harvey P. Dale, Dec 17 2023 *)
PROG
(PFGW64 and SCRIPTIFY)
SCRIPT
DIM nn, 1
DIM kk
DIM jj
DIMS tt
OPENFILEOUT myfile, a(n).txt
OPENFILEOUT myf, b(n).txt
LABEL loopn
SET nn, nn+1
SET jj, 0
IF nn>500 THEN END
SET kk, -1
LABEL loopk
SET kk, kk+2
SETS tt, %d, %d\,; nn; kk
PRP (5^nn-kk)*5^nn-1, tt
IF ISPRP THEN GOTO a
IF ISPRIME THEN GOTO a
GOTO loopk
LABEL a
SET jj, jj+1
PRP (5^nn-kk)*5^nn+1, tt
IF ISPRP THEN GOTO d
IF ISPRIME THEN GOTO d
GOTO loopk
LABEL d
WRITE myfile, tt
SETS tt, %d, %d\,; nn; jj
WRITE myf, tt
GOTO loopn
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Jul 18 2012
STATUS
approved