login
Array read by ascending antidiagonals: A(n, k) is the denominator of (R(n) - k)/(n + k), where R(n) is the digit reversal of n, with A(0, 0) = 1.
3

%I #20 Dec 08 2023 11:38:54

%S 1,1,1,1,1,1,1,3,3,1,1,2,1,2,1,1,5,5,5,5,1,1,3,3,1,3,3,1,1,7,7,7,7,7,

%T 7,1,1,4,2,4,1,4,2,4,1,1,9,9,3,9,9,3,9,9,1,10,5,5,5,5,1,5,5,5,5,1,1,1,

%U 11,11,11,11,11,11,11,11,11,1,4,6,12,2,3,6,1,6,3,2,3,6,1

%N Array read by ascending antidiagonals: A(n, k) is the denominator of (R(n) - k)/(n + k), where R(n) is the digit reversal of n, with A(0, 0) = 1.

%C This array generalizes A367728.

%H Stefano Spezia, <a href="/A367825/b367825.txt">First 151 antidiagonals of the array</a>

%F A(1, n) = A026741(n+1).

%F A(2, n) = A060819(n+2).

%F A(3, n) = A060789(n+3).

%F A(4, n) = A106609(n+4).

%F A(5, n) = A106611(n+5).

%F A(6, n) = A051724(n+6).

%F A(7, n) = A106615(n+7).

%F A(8, n) = A106617(n+8) = A231190(n+16).

%F A(9, n) = A106619(n+9).

%F A(10, n) = A106612(n+10).

%e The array of the fractions begins:

%e 1, -1, -1, -1, -1, -1, -1, -1, ...

%e 1, 0, -1/3, -1/2, -3/5, -2/3, -5/7, -3/4, ...

%e 1, 1/3, 0, -1/5, -1/3, -3/7, -1/2, -5/9, ...

%e 1, 1/2, 1/5, 0, -1/7, -1/4, -1/3, -2/5, ...

%e 1, 3/5, 1/3, 1/7, 0, -1/9, -1/5, -3/11, ...

%e 1, 2/3, 3/7, 1/4, 1/9, 0, -1/11, -1/6, ...

%e 1, 5/7, 1/2, 1/3, 1/5, 1/11, 0, -1/13, ...

%e 1, 3/4, 5/9, 2/5, 3/11, 1/6, 1/13, 0, ...

%e ...

%e The array of the denominators begins:

%e 1, 1, 1, 1, 1, 1, 1, 1, ...

%e 1, 1, 3, 2, 5, 3, 7, 4, ...

%e 1, 3, 1, 5, 3, 7, 2, 9, ...

%e 1, 2, 5, 1, 7, 4, 3, 5, ...

%e 1, 5, 3, 7, 1, 9, 5, 11, ...

%e 1, 3, 7, 4, 9, 1, 11, 6, ...

%e 1, 7, 2, 3, 5, 11, 1, 13, ...

%e 1, 4, 9, 5, 11, 6, 13, 1, ...

%e ...

%t A[0,0]=1; A[n_,k_]:=Denominator[(FromDigits[Reverse[IntegerDigits[n]]]-k)/(n+k)]; Table[A[n-k,k],{n,0,12},{k,0,n}]//Flatten

%Y Cf. A367824 (numerator), A367827 (antidiagonal sums).

%Y Cf. A000012 (n=0), A004086, A026741, A051724, A060789, A060819, A106609, A106611, A106612, A106615, A106617, A231190, A367728 (k=1).

%K nonn,base,frac,tabl

%O 0,8

%A _Stefano Spezia_, Dec 02 2023