login
A046418
Repunit of length a(n) has exactly 7 prime factors (counted with multiplicity).
2
12, 20, 21, 22, 27, 35, 61, 65, 74, 82, 85, 141, 146, 177, 187, 194, 226, 299, 323, 329, 337
OFFSET
1,1
LINKS
Eric Weisstein's World of Mathematics, Repunit
MATHEMATICA
Select[Range[300], PrimeOmega[FromDigits[PadRight[{}, #, 1]]]==7&] (* Harvey P. Dale, Feb 04 2019 *)
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Patrick De Geest, Jul 15 1998
EXTENSIONS
More terms from Robert Gerbicz, Nov 22 2010
Changed offset to 1, a(18) added by Ray Chandler, Apr 23 2017
a(19)-a(21) from Max Alekseyev, May 14 2022
STATUS
approved