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A323334 Sum of distinct products i*j*k with 1 <= i, j, k <= n. 2
1, 15, 90, 310, 990, 2220, 5300, 9660, 17130, 28670, 52848, 75696, 128541, 183393, 257628, 344316, 529038, 683316, 1001110, 1256010, 1607004, 2049490, 2837700, 3330636, 4177186, 5150340, 6273810, 7432702, 9779991, 11124711, 14381168, 16610640, 19542393, 23032799, 26873769 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..2302 (terms 1..500 from Seiichi Manyama)
EXAMPLE
a(2) = 1 + 2 + 4 + 8 = 15.
a(3) = 1 + 2 + 3 + 4 + 6 + 8 + 9 + 12 + 18 + 27 = 90.
MATHEMATICA
a[n_] := Table[i j k, {i, n}, {j, n}, {k, n}] // Flatten // Union // Total;
Array[a, 35] (* Jean-François Alcover, Nov 25 2020 *)
PROG
(Python)
def aupton(terms):
alst, s, pset = [], 0, set()
for n in range(1, terms):
for i in range(1, n+1):
for j in range(i, n+1):
p = i*j*n # k = n
if p not in pset:
pset.add(p)
s += p
alst.append(s)
return alst
print(aupton(36)) # Michael S. Branicky, Jan 15 2021
CROSSREFS
Column 3 of A321163.
Cf. A027425.
Sequence in context: A010822 A316224 A022707 * A151974 A179096 A328994
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jan 11 2019
STATUS
approved

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Last modified June 13 17:32 EDT 2024. Contains 373391 sequences. (Running on oeis4.)