A113720 Concatenation of the numbers of equal successive digits of previous two terms, starting with a(1)=a(2)=1.

1, 1, 2, 11, 12, 31, 1111, 15, 51, 121, 1211, 11212, 114111, 2111213, 21313111, 13111111113, 111114181, 118151111, 5111131114, 2111414131, 1413113111111, 131111111111216, 1111217110111, 13101114111213, 4111214111313111

Offset

1,3

Links

Table of n, a(n) for n=1..25.

Example

As a(6)=1111 and a(7)=15, their digits are 111115, that is (5) 1's followed by (1) 1, so a(8) = 51.

Crossrefs

Cf. A113721.

Sequence in context: A136996 A238109 A374596 * A034118 A140148 A117547

Adjacent sequences: A113717 A113718 A113719 * A113721 A113722 A113723

Keyword

nonn,base

Author

Floor van Lamoen, Nov 08 2005

Extensions

Definition adapted to offset by Georg Fischer, Jun 18 2021

Status

approved