A374716 - OEIS

%I #10 Jul 17 2024 12:29:14

%S 1,5,15,34,58,93,128,175,227,289,349,429,504,592,685,791,891,1014,

%T 1124,1262,1394,1543,1676,1851,2006,2185,2356,2554,2733,2948,3143,

%U 3374,3585,3824,4045,4313,4549,4818,5064,5363,5632,5934,6216,6538,6834,7161,7466,7838,8160,8515,8852,9248,9587,9989

%N Number of distinct sums i^2 + j^2 + k^2 + l^2 for 1<=i<=j<=k<=l<=n.

%o (PARI) a(n) = my(v=vector(4*n^2)); for(i=1, n, for(j=i, n, for(k=j, n, for(l=k, n, v[i^2+j^2+k^2+l^2]+=1)))); sum(i=1, #v, v[i]>0);

%o (Python)

%o def A374716(n): return len({i**2+j**2+k**2+l**2 for i in range(1,n+1) for j in range(i,n+1) for k in range(j,n+1) for l in range(k,n+1)}) # _Chai Wah Wu_, Jul 17 2024

%Y Cf. A061786, A374715.

%K nonn

%O 1,2

%A _Seiichi Manyama_, Jul 17 2024