A079480 a(1) = 1; a(2) = 2; a(n) = LS(a(n-1)) + LS(a(n-2)) if n > 2, where LS(m) = the "Look and Say" description (A045918) of m.

1, 2, 23, 1225, 113428, 2113253433, 1221133328272641, 112221332439252927292834, 2132112312141319233733522435243624342725, 121113122112131112111411131119124449343834282634242925352431253324352529

Offset

1,2

Links

Table of n, a(n) for n=1..10.

Example

E.g. a(7) = LS(a(6))+LS(a(5)). LS(a(6)) = LS(2113253433) = 1221131215131423, LS(a(5)) = LS(113428) = 2113141218 -> a(7) = 1221133328272641

Mathematica

RunLengthEncode[x_List] := (Through[{First, Length}[ #1]] &) /@ Split[x]; LS[n_] := FromDigits[ Reverse[ Flatten[ RunLengthEncode[ Reverse[ IntegerDigits[n]]]]]]; a[1] = 1; a[2] = 2; a[n_] := a[n] = LS[a[n - 1]] + LS[a[n - 2]]; Table[a[n], {n, 1, 10}]

Crossrefs

Cf. A005150, A045918.

Sequence in context: A098633 A015211 A266992 * A239398 A239811 A082963

Adjacent sequences: A079477 A079478 A079479 * A079481 A079482 A079483

Keyword

base,nonn

Author

Joseph L. Pe, Jan 15 2003

Extensions

More terms from Mark Hudson (mrmarkhudson(AT)hotmail.com), Jan 24 2003

Corrected and edited by Robert G. Wilson v, Jan 27 2003

Status

approved