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A354777 Irregular triangle read by rows: T(n,k) is the number of integer quadruples (u,v,w,x) such that u^2+v^2+w^2+x^2 = n and u+v+w+x = k (n>=0, 0 <= k <= A307531(n)). 4

%I #11 Dec 10 2023 09:29:00

%S 1,0,4,12,0,6,0,12,0,4,6,0,8,0,1,0,12,0,12,24,0,24,0,12,0,16,0,12,0,4,

%T 12,0,0,0,6,0,24,0,16,0,12,24,0,30,0,24,0,6,0,12,0,24,0,12,8,0,24,0,

%U 12,0,8,0,24,0,12,0,16,0,4,48,0,24,0,24,0,24,0,36,0,24,0,24,0,12,6,0,0,0,8,0,0,0,1,0,12,0,36,0,12,0,12

%N Irregular triangle read by rows: T(n,k) is the number of integer quadruples (u,v,w,x) such that u^2+v^2+w^2+x^2 = n and u+v+w+x = k (n>=0, 0 <= k <= A307531(n)).

%C Row n has width A307531(n).

%e The triangle begins:

%e [1],

%e [0, 4],

%e [12, 0, 6],

%e [0, 12, 0, 4],

%e [6, 0, 8, 0, 1],

%e [0, 12, 0, 12],

%e [24, 0, 24, 0, 12],

%e [0, 16, 0, 12, 0, 4],

%e [12, 0, 0, 0, 6],

%e [0, 24, 0, 16, 0, 12],

%e [24, 0, 30, 0, 24, 0, 6],

%e [0, 12, 0, 24, 0, 12],

%e [8, 0, 24, 0, 12, 0, 8],

%e [0, 24, 0, 12, 0, 16, 0, 4],

%e [48, 0, 24, 0, 24, 0, 24],

%e [0, 36, 0, 24, 0, 24, 0, 12],

%e [6, 0, 0, 0, 8, 0, 0, 0, 1],

%e [0, 12, 0, 36, 0, 12, 0, 12],

%e [36, 0, 48, 0, 48, 0, 30, 0, 12],

%e ...

%e T(4,2) = 8 from the solutions (u,v,w,x) = (2,0,0,0) (4 such) and (1,1,1,-1) (4 such).

%Y Cf. A000118, A307531.

%Y T(n^2,n) = A354778(n). See also A278085 and A354766.

%K nonn,tabf

%O 0,3

%A _N. J. A. Sloane_, Jun 27 2022

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Last modified August 31 12:30 EDT 2024. Contains 375560 sequences. (Running on oeis4.)