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A167797
Numbers with primitive root 10.
21
7, 17, 19, 23, 29, 47, 49, 59, 61, 97, 109, 113, 131, 149, 167, 179, 181, 193, 223, 229, 233, 257, 263, 269, 289, 313, 337, 343, 361, 367, 379, 383, 389, 419, 433, 461, 487, 491, 499, 503, 509, 529, 541, 571, 577, 593, 619, 647, 659, 701, 709, 727, 743, 811
OFFSET
1,1
COMMENTS
Numbers n such that the decimal expansion of 1/n has period phi(n). For example, 1/49 has period 42.
LINKS
MATHEMATICA
pr=10; Select[Range[2, 2000], MultiplicativeOrder[pr, # ] == EulerPhi[ # ] &]
CROSSREFS
Cf. A001913 (primes with primitive root 10)
Sequence in context: A323746 A101240 A191070 * A001913 A270387 A071845
KEYWORD
nonn
AUTHOR
T. D. Noe, Nov 12 2009
STATUS
approved