A087000 Half length of periodic part of decimal expansion of 1/p for those primes having a periodic part of even length.

3, 1, 3, 8, 9, 11, 14, 23, 29, 30, 4, 22, 48, 2, 17, 54, 56, 21, 65, 4, 23, 74, 39, 83, 89, 90, 96, 49, 15, 111, 114, 116, 15, 25, 128, 131, 134, 14, 73, 156, 55, 168, 58, 16, 183, 93, 189, 191, 194, 100, 102, 209, 70, 216, 16, 76, 230, 77, 243, 245, 249, 251

Offset

1,1

Comments

a(n) appears to be the least k such that 10^k+1 is divisible by A028416(n). See A001271. - Michel Marcus, Aug 13 2023

Links

T. D. Noe, Table of n, a(n) for n = 1..1000

Index entries for sequences related to decimal expansion of 1/n.

Formula

a(n) = A002371(A049084(A028416(n)))/2.

a(n) = A055642(A086999(n))/2.

a(n) = A055642(A087001(n)) = A055642(A087002(n)).

Crossrefs

Cf. A028416, A002371, A086999, A087001, A087002, A001271, A062397 (10^n+1).

Sequence in context: A240665 A068958 A238106 * A289067 A010282 A119265

Adjacent sequences: A086997 A086998 A086999 * A087001 A087002 A087003

Keyword

nonn,base

Author

Reinhard Zumkeller, Jul 29 2003

Status

approved