A366618 - OEIS

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A366618

a(n) = phi(5^n+1), where phi is Euler's totient function (A000010).

10

1, 2, 12, 36, 312, 1040, 7200, 25088, 183808, 557928, 4396800, 15333120, 121680000, 406812744, 2817007200, 8558784000, 76264519680, 254230063200, 1710194342400, 6349120596480, 47334145996800, 127169887444992, 1088029470747648, 3889097389599864

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

LINKS

Max Alekseyev, Table of n, a(n) for n = 0..487

MATHEMATICA

EulerPhi[5^Range[0, 30]+1] (* Harvey P. Dale, Jun 07 2025 *)

PROG

(PARI) {a(n) = eulerphi(5^n+1)}

CROSSREFS

Cf. A000010, A034474, A057939, A074478, A295502, A366615, A366616, A366617.

Cf. A053285, A366579, A366608, A366630, A366639, A366658, A366667, A366669, A366690, A366716.

Sequence in context: A387968 A361570 A294464 * A330781 A185788 A305864

Adjacent sequences: A366615 A366616 A366617 * A366619 A366620 A366621

KEYWORD

nonn

AUTHOR

Sean A. Irvine, Oct 14 2023

STATUS

approved