login

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”).

A055693
Numbers k such that 10^k == -1 (mod k-1).
3
2, 102, 41310, 102690, 309162, 315150, 1000002, 2488530, 4564350, 12679002, 17166870, 28855610, 35049930, 38982870, 42176490, 43232070, 53288510, 64253070, 104439090, 126446850, 130659210, 144379602, 208313490, 252852390, 284335410, 284397750, 337122750, 379257930, 385659630
OFFSET
1,1
MATHEMATICA
Do[If[PowerMod[10, n, n-1]==n-2, Print[n]], {n, 2, 10^8}]
CROSSREFS
Sequence in context: A157066 A202740 A283624 * A357767 A215964 A106299
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jun 09 2000
EXTENSIONS
Corrected and extended by Max Alekseyev, Oct 12 2012
STATUS
approved