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A268387 Bitwise-XOR of the exponents of primes in the prime factorization of n. 16
0, 1, 1, 2, 1, 0, 1, 3, 2, 0, 1, 3, 1, 0, 0, 4, 1, 3, 1, 3, 0, 0, 1, 2, 2, 0, 3, 3, 1, 1, 1, 5, 0, 0, 0, 0, 1, 0, 0, 2, 1, 1, 1, 3, 3, 0, 1, 5, 2, 3, 0, 3, 1, 2, 0, 2, 0, 0, 1, 2, 1, 0, 3, 6, 0, 1, 1, 3, 0, 1, 1, 1, 1, 0, 3, 3, 0, 1, 1, 5, 4, 0, 1, 2, 0, 0, 0, 2, 1, 2, 0, 3, 0, 0, 0, 4, 1, 3, 3, 0, 1, 1, 1, 2, 1, 0, 1, 1, 1, 1, 0, 5, 1, 1, 0, 3, 3, 0, 0, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

Index entries for sequences computed from exponents in factorization of n

FORMULA

a(1) = 0; for n > 1: a(n) = A067029(n) XOR a(A028234(n)). [Here XOR stands for bitwise exclusive-or, A003987.]

Other identities and observations. For all n >= 1:

a(n) <= A267116(n) <= A001222(n).

From Peter Munn, Dec 02 2019 with XOR used as above: (Start)

Defined by: a(p^k) = k, for prime p; a(A059897(n,k)) = a(n) XOR a(k).

a(A052330(n XOR k)) = a(A052330(n)) XOR a(A052330(k)).

a(A019565(n XOR k)) = a(A019565(n)) XOR a(A019565(k)).

(End)

MATHEMATICA

Table[BitXor @@ Map[Last, FactorInteger@ n], {n, 120}] (* Michael De Vlieger, Feb 12 2016 *)

PROG

(Scheme, with memoization-macro definec)

(definec (A268387 n) (cond ((= 1 n) 0) (else (A003987bi (A067029 n) (A268387 (A028234 n)))))) ;; A003987bi implements bitwise-xor (see A003987).

(PARI) a(n) = {my(f = factor(n)); my(b = 0); for (k=1, #f~, b = bitxor(b, f[k, 2]); ); b; } \\ Michel Marcus, Feb 06 2016

CROSSREFS

A003987, A028234, A059897 and A067029 are used to express relationships between sequence terms.

Cf. A268390 (indices of zeros).

Sequences with similar definitions: A267115, A267116.

Differs from A136566 for the first time at n=24, where a(24) = 2, while A136566(24) = 4.

Cf. A019565, A052330.

Sequence in context: A319273 A329615 A272894 * A136566 A330235 A048983

Adjacent sequences:  A268384 A268385 A268386 * A268388 A268389 A268390

KEYWORD

nonn,base

AUTHOR

Antti Karttunen, Feb 05 2016

STATUS

approved

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Last modified April 19 21:57 EDT 2021. Contains 343117 sequences. (Running on oeis4.)