A056214 Primes p whose period of reciprocal equals (p-1)/9.

73, 1423, 1459, 2377, 2503, 3457, 7741, 9433, 10891, 10909, 16057, 17299, 17623, 20269, 21313, 22699, 24103, 26263, 28621, 28927, 29629, 30817, 32257, 34273, 34327, 35461, 35731, 36343, 36793, 37549, 37567, 37657, 38737, 39367, 39979

Offset: 1

Author

Robert G. Wilson v, Aug 02 2000

Keywords

• nonn
• base

Comments

Cyclic numbers of the ninth degree (or ninth order): the reciprocals of these numbers belong to one of nine different cycles. Each cycle has the (number minus 1)/9 digits.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to decimal expansion of 1/n

Crossrefs

Cf. A097443, A055628, A056157, A056210, A056211, A056212, A056213, A056215, A056216, A056217, A098680, A135073.

Programs

Mathematica

f[n_Integer] := Block[{ds = Divisors[n - 1]}, (n - 1)/Take[ ds, Position[ PowerMod[ 10, ds, n], 1] [[1, 1]]] [[ -1]]]; Select[ Prime[ Range[4, 5000]], f[ # ] == 9 &]

Extensions

Edited by N. J. A. Sloane, Apr 30 2007