OFFSET
3,6
LINKS
Hugo Pfoertner, Table of n, a(n) for n = 3..2000
EXAMPLE
a(6) = a(7) = 1: 2*3*6 = 36.
a(8) = 4: 1*2*8 = 16, 2*3*6 = 36, 2*4*8 = 64, 3*6*8 = 144.
PROG
(PARI) a(n) = my(k=0); forsubset([n, 3], s, if(issquare(vecprod(Vec(s))), k++)); k
(Python)
from math import prod
from itertools import combinations
from sympy.ntheory.primetest import is_square
def A373042(n): return sum(1 for p in combinations(range(1, n+1), 3) if is_square(prod(p))) # Chai Wah Wu, May 30 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, May 25 2024
STATUS
approved