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A295501
a(n) = phi(4^n-1), where phi is Euler's totient function (A000010).
14
2, 8, 36, 128, 600, 1728, 10584, 32768, 139968, 480000, 2640704, 6635520, 44717400, 132765696, 534600000, 2147483648, 11452896600, 26121388032, 183250539864, 473702400000, 2427720325632, 8834232287232, 45914084232320, 109586090557440, 656100000000000
OFFSET
1,1
LINKS
Eric Weisstein's World of Mathematics, Totient Function.
FORMULA
a(n) = n*A027695(n).
a(n) = A053287(2*n) = A053285(n) * A053287(n). - Max Alekseyev, Jan 07 2024
MATHEMATICA
EulerPhi[4^Range[30] - 1] (* Paolo Xausa, Jun 17 2024 *)
PROG
(PARI) {a(n) = eulerphi(4^n-1)}
CROSSREFS
phi(k^n-1): A053287 (k=2), A295500 (k=3), this sequence (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: A355104 A248861 A323677 * A283847 A123290 A321110
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 22 2017
STATUS
approved