OFFSET
0,2
COMMENTS
a(2) = 111121 is the first prime in this sequence (compare A242645).
There are no further primes through a(100). - Harvey P. Dale, Sep 12 2014
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..42
FORMULA
a(n) is the concatenation of 1, 11, 121, 11^3, ... 11^(n-1), 11^n.
MAPLE
a:= proc(n) option remember;
`if`(n=0, 1, parse(cat(a(n-1), 11^n)))
end:
seq(a(n), n=0..10); # Alois P. Heinz, May 24 2014
MATHEMATICA
Module[{nn=15, c}, c=IntegerDigits/@(11^Range[0, nn]); Table[FromDigits[ Flatten[ Take[c, n]]], {n, nn+1}]] (* Harvey P. Dale, Sep 12 2014 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, May 23 2014
STATUS
approved