OFFSET
1,1
COMMENTS
Salomaa's first example of an infinite language. - N. J. A. Sloane, Dec 05 2012
If p is a prime and gcd(p,b-1)=1, then (b^p-1)/(b-1) == 1 (mod p); by Fermat's little theorem. For example 1111111 == 1 (mod 7). - Thomas Ordowski, Apr 09 2016
REFERENCES
A. Salomaa, Jewels of Formal Language Theory. Computer Science Press, Rockville, MD, 1981, p. 2. - From N. J. A. Sloane, Dec 05 2012
LINKS
N. J. A. Sloane, Table of n, a(n) for n = 1..50
Fanel Iacobescu, Smarandache Partition Type Sequences, in Bulletin of Pure and Applied Sciences, India, Vol. 16E, No. 2, 1997, pp. 237-240
M. Le and K. Wu, The Primes in the Smarandache Unary Sequence, Smarandache Notions Journal, Vol. 9, No. 1-2. 1998, 98-99.
Eric Weisstein's World of Mathematics, Smarandache Sequences
FORMULA
a(n) = (10^prime(n) - 1)/9. - Vincenzo Librandi, May 29 2014
MAPLE
f:=n->(10^ithprime(n)-1)/9; [seq(f(n), n=1..20)]; # N. J. A. Sloane, Dec 05 2012
MATHEMATICA
Table[FromDigits[PadRight[{}, Prime[n], 1]], {n, 15}] (* Harvey P. Dale, Apr 10 2012 *)
PROG
(Magma) [(10^p-1)/9: p in PrimesUpTo(40)]; // Vincenzo Librandi, May 29 2014
CROSSREFS
KEYWORD
nonn,easy,base
AUTHOR
J. Castillo (arp(AT)cia-g.com) [Broken email address?]
EXTENSIONS
More terms from Erich Friedman
Corrected and extended by Harvey P. Dale, Apr 10 2012
STATUS
approved