cp's OEIS Frontend

A128540 Triangle A127647 * A097806, read by rows.

%I A128540 #14 Jun 07 2025 23:55:32
%S A128540 1,1,1,0,2,2,0,0,3,3,0,0,0,5,5,0,0,0,0,8,8,0,0,0,0,0,13,13,0,0,0,0,0,
%T A128540 0,21,21,0,0,0,0,0,0,0,34,34,0,0,0,0,0,0,0,0,55,55,0,0,0,0,0,0,0,0,0,
%U A128540 89,89,0,0,0,0,0,0,0,0,0,0,144,144
%N A128540 Triangle A127647 * A097806, read by rows.
%C A128540 Row sums = A094895 starting (1, 2, 4, 6, 10, 16, 26, ...). A128541 = A097806 * A127647.
%H A128540 G. C. Greubel, <a href="/A128540/b128540.txt">Rows n = 1..100 of triangle, flattened</a>
%F A128540 A127646 * A097806 as infinite lower triangular matrices.
%e A128540 First few rows of the triangle:
%e A128540   1;
%e A128540   1, 1;
%e A128540   0, 2, 2;
%e A128540   0, 0, 3, 3;
%e A128540   0, 0, 0, 5, 5;
%e A128540   0, 0, 0, 0, 8, 8;
%e A128540   ...
%t A128540 Table[If[k==n || k==n-1, Fibonacci[n], 0], {n, 15}, {k, n}]//Flatten (* _G. C. Greubel_, Jul 11 2019 *)
%o A128540 (PARI) T(n,k) = if(k==n || k==n-1, fibonacci(n), 0); \\ _G. C. Greubel_, Jul 11 2019
%o A128540 (Magma) [k eq n select Fibonacci(n) else k eq n-1 select Fibonacci(n) else 0: k in [1..n], n in [1..15]]; // _G. C. Greubel_, Jul 11 2019
%o A128540 (Sage)
%o A128540 def T(n, k):
%o A128540     if (k==n): return fibonacci(n)
%o A128540     elif (k==n-1): return fibonacci(n)
%o A128540     else: return 0
%o A128540 [[T(n, k) for k in (1..n)] for n in (1..15)] # _G. C. Greubel_, Jul 11 2019
%Y A128540 Cf. A127647, A097806, A128541.
%K A128540 nonn,tabl,easy
%O A128540 1,5
%A A128540 _Gary W. Adamson_, Mar 10 2007