A125605 Triangle read by rows: T(n,k) = (T(n-1,k-1) + T(n-1,k)) / gcd(T(n-1,k-1), T(n-1,k)).

1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 2, 4, 1, 1, 5, 3, 3, 5, 1, 1, 6, 8, 2, 8, 6, 1, 1, 7, 7, 5, 5, 7, 7, 1, 1, 8, 2, 12, 2, 12, 2, 8, 1, 1, 9, 5, 7, 7, 7, 7, 5, 9, 1, 1, 10, 14, 12, 2, 2, 2, 12, 14, 10, 1, 1, 11, 12, 13, 7, 2, 2, 7, 13, 12, 11, 1, 1, 12, 23, 25, 20, 9, 2, 9, 20, 25, 23, 12, 1, 1, 13

Offset

0,5

Comments

Row A264856(n) contains the first occurrence of n, n > 0. - Reinhard Zumkeller, Nov 26 2015

Links

T. D. Noe, Rows n=0..100, flattened

Prog

(Haskell)
a125605 n k = a125605_tabl !! n !! k
a125605_row n = a125605_tabl !! n
a125605_tabl = iterate f [1] where
   f xs = zipWith (\v w -> (v + w) `div` gcd v w) ([0] ++ xs) (xs ++ [0])
-- Reinhard Zumkeller, Nov 26 2015

Crossrefs

Cf. A007318, A125606.

Cf. A040000 (central terms), A131134, A264856.

Sequence in context: A177974 A095140 A225043 * A110570 A341314 A335174

Adjacent sequences: A125602 A125603 A125604 * A125606 A125607 A125608

Keyword

nonn,tabl

Author

Franklin T. Adams-Watters, Nov 27 2006

Status

approved