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A366663
a(n) = phi(9^n-1), where phi is Euler's totient function (A000010).
14
4, 32, 288, 2560, 26400, 165888, 2384928, 15728640, 141087744, 1246080000, 14758128000, 85996339200, 1270928131200, 8810420097024, 70207948800000, 677066362060800, 8218041445152000, 43129128265187328, 674757689572915200, 4238841176064000000
OFFSET
1,1
LINKS
FORMULA
a(n) = A295500(2*n) = 2 * A295500(n) * A366579(n). - Max Alekseyev, Jan 07 2024
MATHEMATICA
EulerPhi[9^Range[30] - 1]
PROG
(PARI) {a(n) = eulerphi(9^n-1)}
CROSSREFS
phi(k^n-1): A053287 (k=2), A295500 (k=3), A295501 (k=4), A295502 (k=5), A366623 (k=6), A366635 (k=7), A366654 (k=8), this sequence (k=9), A295503 (k=10), A366685 (k=11), A366711 (k=12).
Sequence in context: A199566 A370160 A372464 * A110901 A295538 A256183
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 15 2023
STATUS
approved