A225261 Number of distinct values of the sum of 4 products of three 0..n integers.

5, 28, 90, 205, 409, 694, 1123, 1668, 2396, 3298, 4442, 5741, 7410, 9266, 11443, 13937, 16857, 20031, 23746, 27694, 32236, 37143, 42619, 48390, 55021, 62036, 69617, 77815, 86744, 96000, 106372, 117136, 128823, 141110, 154192, 167871, 182867, 198285

Offset: 1

Author

R. H. Hardin, May 04 2013

Keywords

• nonn

Links

• R. H. Hardin, Table of n, a(n) for n = 1..138

Crossrefs

Cf. A027426.

Row 4 of A225258.

Programs

Python

from itertools import combinations_with_replacement as mc
def a(n):
  prods = set(a*b*c for a, b, c in mc(range(n+1), 3))
  return len(set(sum(p) for p in mc(prods, 4)))
print([a(n) for n in range(1, 11)]) # Michael S. Branicky, May 28 2021