A242645 a(n) = concatenation of decimal expansions of powers of 11 (in decreasing order).

1, 111, 121111, 1331121111, 146411331121111, 161051146411331121111, 1771561161051146411331121111, 194871711771561161051146411331121111, 214358881194871711771561161051146411331121111, 2357947691214358881194871711771561161051146411331121111

Offset: 0

Author

N. J. A. Sloane, May 23 2014

Keywords

• nonn
• base

Comments

A068704(11) (presently unknown) is either 0, if every term here is composite, or the index of the first prime in the sequence.

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..42

Crossrefs

Cf. A068704, A242646.

Programs

Maple

a:= proc(n) option remember;
      `if`(n=0, 1, parse(cat(11^n, a(n-1))))
    end:
seq(a(n), n=0..10);  # Alois P. Heinz, May 24 2014

Formula

a(n) is the concatenation of 11^n, 11^(n-1), ..., 121, 11, 1.