A212488 Smallest k>0 such that (5^n-k)*5^n-1 and (5^n-k)*5^n+1 are a twin prime pair or 0 if no such k exists.

0, 1, 11, 1, 17, 85, 17, 25, 71, 25, 83, 673, 3623, 1069, 401, 1225, 1361, 409, 3449, 2581, 779, 613, 605, 781, 395, 5797, 17, 6967, 755, 361, 3443, 5467, 6857, 679, 53, 9355, 3287, 2941, 22385, 6091, 8423, 685, 13649, 2437, 113, 19393, 19781, 12253, 53603, 21049, 5321, 2149, 21779

Offset: 1

Author

Pierre CAMI, Jul 18 2012

Keywords

• nonn

Comments

Conjecture: There is always one such k if n>1.

Links

• Pierre CAMI, Table of n, a(n) for n = 1..501

Crossrefs

Cf. A212487

Programs

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 *)