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 A100371 a(n) = 2^phi(n) - 1 = A066781(n) - 1. 7
 1, 1, 3, 3, 15, 3, 63, 15, 63, 15, 1023, 15, 4095, 63, 255, 255, 65535, 63, 262143, 255, 4095, 1023, 4194303, 255, 1048575, 4095, 262143, 4095, 268435455, 255, 1073741823, 65535, 1048575, 65535, 16777215, 4095, 68719476735, 262143, 16777215, 65535 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Number of nonempty subsets of reduced residue system [RRS(n)] modulo n. LINKS T. D. Noe, Table of n, a(n) for n = 1..1000 N. Bliss, B. Fulan, S. Lovett, and J. Sommars, Strong Divisibility, Cyclotomic Polynomials, and Iterated Polynomials, Amer. Math. Monthly, 120 (2013), 519-536. FORMULA a(n) = Sum_{i=1..n} binomial(phi(n), i). - Enrique Pérez Herrero, Mar 10 2012 MAPLE A100371:=n->2^numtheory[phi](n)-1: seq(A100371(n), n=1..60); # Wesley Ivan Hurt, Apr 14 2017 MATHEMATICA Table[2^EulerPhi[n] - 1, {n, 1, 50}] PROG (PARI) a(n) = 2^eulerphi(n) - 1; \\ Michel Marcus, Apr 14 2017 (Python) from sympy import totient def a(n): return 2**totient(n) - 1 # Indranil Ghosh, Apr 14 2017 CROSSREFS Cf. A000010, A066781. Sequence in context: A260119 A282009 A282485 * A286206 A286501 A287100 Adjacent sequences:  A100368 A100369 A100370 * A100372 A100373 A100374 KEYWORD easy,nonn AUTHOR Labos Elemer, Nov 30 2004 EXTENSIONS Entry revised by N. J. A. Sloane, Jun 07 2013 STATUS approved

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Last modified June 4 08:18 EDT 2020. Contains 334825 sequences. (Running on oeis4.)