A197224 Exponent in the power of 2 which is the period of the decimal fraction 1/A072982(n).

0, 1, 4, 3, 2, 3, 8, 5, 5, 5, 5, 9, 8, 6, 16, 5, 8, 6, 10, 16, 4, 6, 9, 17, 20, 21, 18, 10, 13, 19, 7, 27, 9, 30, 9, 12, 20, 30, 36, 20, 41, 23, 42, 41, 6

Offset: 1

Author

T. D. Noe, Oct 21 2011

Keywords

• nonn
• base
• hard
• more

Comments

This means that the fraction 1/52613349377 repeats every 2^30 terms!

Every term with value up to 6 is accounted for.

Links

• Hans Riesel, Some factors of the numbers Gn = 6^2^n+1 and Hn = 10^2^n+1, Math. Comp. 23 (1969), pp. 413-415. With errata reported in Math. Comp. 24 (1970), p. 243.

Crossrefs

Cf. A072982, A274512.

Programs

Mathematica

Table[Log[2, MultiplicativeOrder[10, p]], {p, A072982}] (* Ray Chandler, Oct 25 2019 *)

Formula

a(n+1) = A274512(n) + 1. - Ray Chandler, Oct 25 2019

Extensions

a(37)-a(39) from Ray Chandler, Nov 03 2011

a(40)-a(45) from Ray Chandler, Oct 25 2019