A111864 Define the first three terms to be 1, 1 and 1. All the other terms are obtained by concatenating the three previous terms.

1, 1, 1, 111, 11111, 111111111, 11111111111111111, 1111111111111111111111111111111, 111111111111111111111111111111111111111111111111111111111

Offset

0,4

Links

Table of n, a(n) for n=0..8.

Formula

a(n) = A002275(A000213(n)), the repunits with the property that their number of digits is a tribonacci number. - Stefan Steinerberger, Jan 27 2006

Example

The first three terms are 1,1,1. The fourth term is 111 - which is obtained by concatenating the first three terms.

Mathematica

nxt[{a_, b_, c_}]:={b, c, FromDigits[Join[Flatten[IntegerDigits/@{a, b, c}]]]}; Transpose[NestList[nxt, {1, 1, 1}, 10]][[1]] (* Harvey P. Dale, Feb 18 2013 *)

Crossrefs

Cf. A000213, A002275.

Sequence in context: A100706 A259102 A262629 * A098034 A109242 A349805

Adjacent sequences: A111861 A111862 A111863 * A111865 A111866 A111867

Keyword

nonn,easy,base

Author

Parthasarathy Nambi, Nov 22 2005

Extensions

More terms from Stefan Steinerberger, Jan 27 2006

Status

approved