A076246 Totients of those numbers at which values of A051547 increase: in these consecutive terms new prime powers arise, i.e., which did not occur in neither of preceding terms.

2, 4, 6, 10, 8, 16, 18, 22, 28, 46, 32, 52, 58, 54, 82, 64, 100, 102, 106, 148, 162, 166, 172, 178, 190, 196, 226, 250, 128, 256, 262, 268, 282, 292, 310, 316, 346, 358, 366, 382, 388, 466, 478, 486, 502, 508, 556, 562, 568, 586, 606, 618, 642, 652, 676, 708

Offset: 1

Author

Labos Elemer, Oct 08 2002

Keywords

• nonn

Examples

			8 = 2*2*2 immediately follows 10 = 2*5; 58 = 2*29 follows 52 = 2*2*13. In both cases, the latter term has a new prime factor (like 29) or an old one at a higher power (like 2*2*2).
		

Crossrefs

Cf. A003418, A051451, A051547, A076244, A076245.

Programs

Mathematica

s0=1; s1=1; Do[s0=s1; s1=LCM[s1, EulerPhi[n]]; If[ !Equal[s0, s1], Print[n]], {n, 1, 1000}]

PARI

lista(nn) = {least = 1; for (n=2, nn, nleast = lcm(least, eulerphi(n)); if (nleast > least, print1(eulerphi(n), ", ")); least = nleast;);} \\ Michel Marcus, Jul 30 2017

Formula

a(n) = phi(A076245(n + 1)). - Sean A. Irvine, Mar 25 2025