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A366666
Sum of the divisors of 9^n+1.
12
3, 18, 126, 1332, 10476, 109926, 816732, 8906760, 64570086, 706911048, 5357742012, 56496274632, 456919958880, 4661686010664, 35152280388792, 388532214509688, 2779530283277766, 30018958465575240, 230668806145962744, 2431533550553980488, 19410628990783168944
OFFSET
0,1
LINKS
FORMULA
a(n) = sigma(9^n+1) = A000203(A062396(n)).
a(n) = A366578(2*n). - Max Alekseyev, Jan 08 2024
EXAMPLE
a(2)=126 because 9^2+1 has divisors {1, 2, 41, 82}.
MAPLE
a:=n->numtheory[sigma](9^n+1):
seq(a(n), n=0..100);
MATHEMATICA
DivisorSigma[1, 9^Range[0, 20] + 1] (* Paul F. Marrero Romero, Nov 14 2023 *)
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 15 2023
STATUS
approved