A197224 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

COMMENTS

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

Every term with value up to 6 is accounted for.

LINKS

Table of n, a(n) for n=1..45.

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.

FORMULA

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

MATHEMATICA

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

CROSSREFS

Cf. A072982, A274512.

Sequence in context: A183197 A245459 A001368 * A340739 A196519 A184338

Adjacent sequences: A197221 A197222 A197223 * A197225 A197226 A197227

KEYWORD

nonn,base,hard,more

AUTHOR

T. D. Noe, Oct 21 2011

EXTENSIONS

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

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

STATUS

approved