A125058 - OEIS

A125058

A sequence of words over an alphabet of two letters: a(0) = 1, a(1) = 2; a(n+2) = a(n+1)a(n)a(n+1).

1, 2, 212, 2122212, 21222122122122212, 21222122122122212212221221222122122122212, 212221221221222122122212212221221221222122122212212212221221222122122122212212221221222122122122212

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

A055642(a(n)) = A001333(n). - Reinhard Zumkeller, Feb 02 2007

REFERENCES

Suggested by a posting by Igor G. Korepanov to "Jim's Forum", Jan 10 2007.

LINKS

Table of n, a(n) for n=0..6.

FORMULA

a(n)=(a(n-1)*A011557(A001333(n-2))+a(n-2))*A011557(A001333(n-2))+a(n-1). - Reinhard Zumkeller, Feb 02 2007

MATHEMATICA

nxt[{a_, b_}]:={b, FromDigits[Flatten[Join[IntegerDigits[b], IntegerDigits[a], IntegerDigits[ b]]]]}; NestList[nxt, {1, 2}, 7][[All, 1]] (* Harvey P. Dale, Jun 05 2021 *)

CROSSREFS

Sequence in context: A181903 A345397 A078280 * A202741 A239529 A101393

Adjacent sequences: A125055 A125056 A125057 * A125059 A125060 A125061

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Jan 10 2007

STATUS

approved