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 A069177 Maximal power of 2 that divides Phi(n), or the size of the Sylow 2-subgroup of the group of units mod n. 3
 1, 1, 2, 2, 4, 2, 2, 4, 2, 4, 2, 4, 4, 2, 8, 8, 16, 2, 2, 8, 4, 2, 2, 8, 4, 4, 2, 4, 4, 8, 2, 16, 4, 16, 8, 4, 4, 2, 8, 16, 8, 4, 2, 4, 8, 2, 2, 16, 2, 4, 32, 8, 4, 2, 8, 8, 4, 4, 2, 16, 4, 2, 4, 32, 16, 4, 2, 32, 4, 8, 2, 8, 8, 4, 8, 4, 4, 8, 2, 32, 2, 8, 2, 8, 64, 2, 8, 8, 8, 8, 8, 4, 4, 2, 8, 32 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 FORMULA a(n) = 2^A053574(n). Multiplicative with a(2^e) = 2^(e-1) and a(p^e) = power of 2 in prime factorization of p - 1 for an odd prime p. - Vladeta Jovovic, Apr 10 2002 MATHEMATICA Table[2^IntegerExponent[EulerPhi@ n, 2], {n, 96}] (* Michael De Vlieger, Aug 23 2017 *) PROG (Scheme) (define (A069177 n) (cond ((= 1 n) n) ((zero? (modulo n 4)) (* 2 (A069177 (/ n 2)))) ((even? n) (A069177 (/ n 2))) (else (* (A006519 (+ -1 (A020639 n))) (A069177 (A028234 n)))))) ;; (After Jovovic's multiplicative formula) - Antti Karttunen, Aug 22 2017 CROSSREFS Cf. A000010, A006519, A053574, A023506. Sequence in context: A088200 A073103 A247257 * A077659 A212595 A087692 Adjacent sequences:  A069174 A069175 A069176 * A069178 A069179 A069180 KEYWORD nonn,mult AUTHOR Sharon Sela (sharonsela(AT)hotmail.com), Apr 09 2002 EXTENSIONS More terms from Vladeta Jovovic, Apr 10 2002 STATUS approved

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Last modified August 4 19:54 EDT 2020. Contains 336202 sequences. (Running on oeis4.)