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A366607
Sum of the divisors of 4^n+1.
11
3, 6, 18, 84, 258, 1302, 4356, 20520, 65538, 351120, 1110276, 5048232, 17041416, 82623888, 284225796, 1494039792, 4301668356, 20788904016, 73234343952, 332019460560, 1103789883396, 5936210280000, 18679788287496, 84884999116320, 282937726148616
OFFSET
0,1
LINKS
FORMULA
a(n) = sigma(4^n+1) = A000203(A052539(n)).
a(n) = A069061(2*n). - Max Alekseyev, Jan 08 2024
EXAMPLE
a(3)=84 because 4^3+1 has divisors {1, 5, 13, 65}.
MAPLE
a:=n->numtheory[sigma](4^n+1):
seq(a(n), n=0..100);
MATHEMATICA
DivisorSigma[1, 4^Range[0, 30]+1] (* Paolo Xausa, Oct 14 2023 *)
PROG
(Python)
from sympy import divisor_sigma
def A366607(n): return divisor_sigma((1<<(n<<1))+1) # Chai Wah Wu, Oct 14 2023
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 14 2023
STATUS
approved