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A198069 Table read by rows, T(0,0) = 1 and for n>0, 0<=k<=2^(n-1) T(n,k) = gcd(k,2^(n-1)). 5
1, 1, 1, 2, 1, 2, 4, 1, 2, 1, 4, 8, 1, 2, 1, 4, 1, 2, 1, 8, 16, 1, 2, 1, 4, 1, 2, 1, 8, 1, 2, 1, 4, 1, 2, 1, 16, 32, 1, 2, 1, 4, 1, 2, 1, 8, 1, 2, 1, 4, 1, 2, 1, 16, 1, 2, 1, 4, 1, 2, 1, 8, 1, 2, 1, 4, 1, 2, 1, 32, 64, 1, 2, 1, 4, 1, 2, 1, 8, 1, 2, 1, 4, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Reinhard Zumkeller, Rows n = 0..13 of triangle, flattened

FORMULA

For n > 0: Let S be the n-th row, S' = replace the initial term by its double, then row (n+1) = concatenation of S' and the reverse of S' without the initial term. - Reinhard Zumkeller, May 26 2013

EXAMPLE

                         1

                        1, 1

                      2, 1, 2

                   4, 1, 2, 1, 4

             8, 1, 2, 1, 4, 1, 2, 1, 8

16, 1, 2, 1, 4, 1, 2, 1, 8, 1, 2, 1, 4, 1, 2, 1, 16

MAPLE

# In triangular form:

seq(print(seq(gcd(k, 2^(n-1)), k=0..2^(n-1))), n=0..6);

PROG

(Haskell)

a198069 n k = a198069_tabf !! n !! k

a198069_row n = a198069_tabf !! n

a198069_tabf = [0] : iterate f [1, 1] where

   f (x:xs) = ys ++ tail (reverse ys) where ys = (2 * x) : xs

-- Reinhard Zumkeller, May 26 2013

CROSSREFS

Cf. A094373 (row lengths), A045623 (row sums), A011782 (edges and central terms).

Sequence in context: A105245 A105246 A193829 * A300792 A132082 A129644

Adjacent sequences:  A198066 A198067 A198068 * A198070 A198071 A198072

KEYWORD

nonn,tabf

AUTHOR

Peter Luschny, Nov 12 2011

STATUS

approved

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Last modified March 22 12:46 EDT 2019. Contains 321421 sequences. (Running on oeis4.)