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A083671 Array read by rows in which each row describes in words the composition of the previous row. 3
1, 1, 1, 2, 1, 1, 1, 1, 2, 3, 1, 1, 2, 2, 1, 1, 2, 1, 3, 3, 1, 2, 2, 1, 3, 2, 1, 2, 2, 2, 3, 1, 1, 4, 2, 1, 3, 3, 1, 1, 2, 1, 3, 1, 4, 4, 1, 1, 2, 2, 3, 1, 4, 3, 1, 2, 2, 1, 3, 2, 4, 2, 1, 3, 2, 2, 3, 1, 4, 2, 1, 3, 2, 2, 3, 1, 4, 2, 1, 3, 2, 2, 3, 1, 4, 2, 1, 3, 2, 2, 3, 1, 4, 2, 1, 3, 2, 2, 3, 1, 4, 2, 1, 3, 2, 2, 3, 1, 4, 2, 1, 3, 2, 2, 3, 1, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..1000

FORMULA

Becomes periodic at row 13.

G.f.: x*(x^67 -x^65 -x^63 +x^61 -x^59 +x^57 -x^55 +x^53 -x^49 -x^45 -x^44 -x^42 +3*x^41 -x^40 +2*x^38 -x^37 -x^36 +x^35 -x^34 -2*x^33 +2*x^32 -x^30 -x^28 +x^27 +2*x^26 -x^25 -x^24 -x^22 +x^20 -2*x^19 -2*x^18 +2*x^17 -x^13 -x^12 +x^11 -2*x^9 -x^8 -x^7 -x^6 -x^5 -x^4 -2*x^3 -x^2 -x -1) / (x^8-1). - Alois P. Heinz, Jul 25 2013

EXAMPLE

Array begins:

1

1 1

2 1

1 1 1 2

3 1 1 2

2 1 1 2 1 3

3 1 2 2 1 3

2 1 2 2 2 3

1 1 4 2 1 3

3 1 1 2 1 3 1 4

4 1 1 2 2 3 1 4

3 1 2 2 1 3 2 4

2 1 3 2 2 3 1 4

Explanation: look at 3 1 1 2. What do you see? Two 1's, one 2 and one 3, so the next row is 2 1 1 2 1 3.

MATHEMATICA

NestList[Function[test, Flatten[{Count[test, # ], # } & /@ Union[test]]], {1}, 13]

RunLengthEncode[x_List ] := (Through[ { Length, First}[ #1 ] ] &) /@ Split[ Sort[ x ]]; LookAndSay[ n_, d_:1 ] := NestList[ Flatten[ RunLengthEncode[ # ] ] &, {d}, n - 1 ]; F[n_] := LookAndSay[ n, 1 ][[ n ]]; Flatten[ Table[ F[n], {n, 18}]] (* Robert G. Wilson v, Jan 22 2004 *)

CROSSREFS

Similar to A005151. Cf. A005150, A034002, A034003.

Sequence in context: A303694 A194673 A240595 * A201913 A232463 A270000

Adjacent sequences:  A083668 A083669 A083670 * A083672 A083673 A083674

KEYWORD

nonn,tabf,easy,base

AUTHOR

N. J. A. Sloane, based on a query from Chasity Engle, Jan 20 2004

EXTENSIONS

More terms from Wouter Meeussen and Robert G. Wilson v, Jan 22 2004

STATUS

approved

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Last modified January 20 21:36 EST 2019. Contains 319336 sequences. (Running on oeis4.)