OFFSET
6,1
COMMENTS
EXAMPLE
MATHEMATICA
Table[Last@Select[Divisors[(n - 5)*(n + 5)], Mod[#, 5] != 0 &], {n, 6,
56}] (* Giorgos Kalogeropoulos, Nov 19 2021 *)
Table[(n - 5)*(n + 5)/5^IntegerExponent[(n - 5)*(n + 5), 5], {n, 6, 56}] (* Amiram Eldar, Nov 22 2021 *)
PROG
(PARI) A132739(n)=n/5^valuation(n, 5);
a(n) = A132739((n-5)*(n+5));
[a(n)|n<-[6..25]]
(Ruby) p (6..25).map { |n| x = (n-5)*(n+5); x /= 5 while (x % 5) == 0; x }
(Python)
def A349487(n):
a, b = divmod(n*n-25, 5)
while b == 0:
a, b = divmod(a, 5)
return 5*a+b # Chai Wah Wu, Dec 05 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Simon Strandgaard, Nov 19 2021
STATUS
approved