A374714 Number of distinct sums i^3 + j^3 + k^3 + l^3 for 1<=i<=j<=k<=l<=n.
1, 5, 15, 35, 70, 119, 202, 317, 473, 671, 902, 1138, 1515, 2008, 2521, 3039, 3758, 4592, 5539, 6657, 7879, 9209, 10797, 12304, 14243, 16371, 18348, 21006, 23816, 26563, 29848, 33046, 36698, 40190, 44885, 49068, 54040, 59479, 64762, 70420, 76810, 83414, 90659, 98158, 105838, 114127, 123048
Offset: 1
Keywords
Programs
-
PARI
a(n) = my(v=vector(4*n^3)); for(i=1, n, for(j=i, n, for(k=j, n, for(l=k, n, v[i^3+j^3+k^3+l^3]+=1)))); sum(i=1, #v, v[i]>0);
-
Python
def A374714(n): return len({i**3+j**3+k**3+l**3 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 18 2024