A001270 Table of prime factors of 10^n - 1 (with multiplicity).

3, 3, 3, 3, 11, 3, 3, 3, 37, 3, 3, 11, 101, 3, 3, 41, 271, 3, 3, 3, 7, 11, 13, 37, 3, 3, 239, 4649, 3, 3, 11, 73, 101, 137, 3, 3, 3, 3, 37, 333667, 3, 3, 11, 41, 271, 9091, 3, 3, 21649, 513239, 3, 3, 3, 7, 11, 13, 37, 101, 9901, 3, 3, 53, 79, 265371653

Offset

1,1

Comments

The length of the n-th row is A057951(n).

References

J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 2nd edition, 1985; and later supplements.

Links

Max Alekseyev, Rows n = 1..352, flattened

J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.

Makoto Kamada, Factorizations of 11...11 (Repunit).

S. S. Wagstaff, Jr., The Cunningham Project

Mathematica

Table[f = FactorInteger[10^n - 1]; Flatten[Table[Table[i[[1]], {i[[2]]}], {i, f}]], {n, 13}] (* T. D. Noe, Jun 27 2012 *)

Crossrefs

Cf. A002283.

Sequence in context: A337328 A201700 A087575 * A029630 A342400 A349924

Adjacent sequences: A001267 A001268 A001269 * A001271 A001272 A001273

Keyword

nonn,tabf

Author

N. J. A. Sloane

Extensions

Erroneous b-file replaced by Ray Chandler, Apr 26 2017

b-file corrected and extended with rows 323..352 by Max Alekseyev, May 23 2023

Status

approved