A295501 a(n) = phi(4^n-1), where phi is Euler's totient function (A000010).

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

Max Alekseyev, Table of n, a(n) for n = 1..1122

Eric Weisstein's World of Mathematics, Totient Function.

Wikipedia, Euler's 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

Cf. A000010, A053285.

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).

Cf. A366602, A366603, A366604, A366608.

Sequence in context: A355104 A248861 A323677 * A283847 A123290 A321110

Adjacent sequences: A295498 A295499 A295500 * A295502 A295503 A295504

Keyword

nonn

Author

Seiichi Manyama, Nov 22 2017

Status

approved