login
Triangle read by rows: n-th row consists of n copies of the n-th nonzero Fibonacci number.
5

%I #19 Nov 09 2024 01:14:03

%S 1,2,2,3,3,3,5,5,5,5,8,8,8,8,8,13,13,13,13,13,13,21,21,21,21,21,21,21,

%T 34,34,34,34,34,34,34,34,55,55,55,55,55,55,55,55,55,89,89,89,89,89,89,

%U 89,89,89,89,144,144,144,144,144,144,144,144,144,144,144,233,233,233,233,233,233,233,233,233,233,233,233

%N Triangle read by rows: n-th row consists of n copies of the n-th nonzero Fibonacci number.

%H Reinhard Zumkeller, <a href="/A108035/b108035.txt">Rows n = 1..120 of triangle, flattened</a>

%F G.f.: (1+x+y)/((1-x-x^2)*(1-y-y^2)). [U coordinates]

%e 1; 2,2; 3,3,3; 5,5,5,5; 8,8,8,8,8; ...

%t Flatten[Table[Table[Fibonacci[n],{n-1}],{n,13}]] (* _Harvey P. Dale_, Jul 18 2015 *)

%o (Haskell)

%o a108035 n k = a108035_tabl !! (n-1) !! (n-1)

%o a108035_row n = a108035_tabl !! (n-1)

%o a108035_tabl = zipWith replicate [1..] $ drop 2 a000045_list

%o -- _Reinhard Zumkeller_, Oct 07 2012

%o (Python)

%o from math import isqrt

%o from sympy import fibonacci

%o def A108035(n): return int(fibonacci(1+(m:=isqrt(k:=n<<1))+(k>m*(m+1)))) # _Chai Wah Wu_, Nov 07 2024

%Y Cf. A000045, A039913, A108036, A108037.

%Y Cf. A023607 (row sums).

%K nonn,tabl,changed

%O 1,2

%A _N. J. A. Sloane_, Jun 01 2005

%E Definition clarified by _N. J. A. Sloane_, Nov 09 2024