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A295500
a(n) = phi(3^n-1), where phi is Euler's totient function (A000010).
13
1, 4, 12, 32, 110, 288, 1092, 2560, 9072, 26400, 84700, 165888, 797160, 2384928, 6019200, 15728640, 64533700, 141087744, 580765248, 1246080000, 4823425152, 14758128000, 46070066188, 85996339200, 385087175000, 1270928131200, 3474144608256, 8810420097024
OFFSET
1,2
LINKS
Eric Weisstein's World of Mathematics, Totient Function
FORMULA
a(n) = n*A027385(n).
a(n) = A000010(A024023(n)). - Michel Marcus, Jun 18 2024
MATHEMATICA
EulerPhi[3^Range[30] - 1] (* Paolo Xausa, Jun 18 2024 *)
PROG
(PARI) {a(n) = eulerphi(3^n-1)}
CROSSREFS
phi(k^n-1): A053287 (k=2), this sequence (k=3), A295501 (k=4), A295502 (k=5), A366623 (k=6), A366635 (k=7), A366654 (k=8), A366663 (k=9), A295503 (k=10), A366685 (k=11), A366711 (k=12).
Sequence in context: A001665 A066536 A265212 * A168078 A225894 A318637
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 22 2017
STATUS
approved