OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
Anton Shakov, Polynomials in Z[x] whose divisors are enumerated by SL_2(N_0), arXiv:2405.03552 [math.NT], 2024.
FORMULA
EXAMPLE
a(7) = 6 because 7^2 + 1 = 50 and the 6 divisors are {1, 2, 5, 10, 25, 50}.
MAPLE
with(numtheory):for n from 0 to 110 do:n1:=nops(divisors(n^2+1)):s:=0:for m from 1 to n1 do: s:=s+1:od: printf(`%d, `, s):od:
MATHEMATICA
Array[DivisorSigma[0, #^2 + 1] &, 85, 0] (* Michael De Vlieger, Mar 17 2018 *)
PROG
(PARI) a(n) = numdiv(n^2+1); \\ Michel Marcus, Mar 16 2018
(Python)
from sympy import divisor_count
def A193432(n): return divisor_count(n**2+1) # Chai Wah Wu, Apr 17 2025
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Jul 28 2011
STATUS
approved
