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 A091248 Number of irreducible factors in the factorization of X^n + 1 over GF(2) (counted with multiplicity). 3
 1, 2, 2, 4, 2, 4, 3, 8, 3, 4, 2, 8, 2, 6, 5, 16, 3, 6, 2, 8, 6, 4, 3, 16, 3, 4, 4, 12, 2, 10, 7, 32, 5, 6, 6, 12, 2, 4, 5, 16, 3, 12, 4, 8, 8, 6, 3, 32, 5, 6, 8, 8, 2, 8, 5, 24, 5, 4, 2, 20, 2, 14, 13, 64, 7, 10, 2, 12, 6, 12, 3, 24, 9, 4, 8, 8, 6, 10, 3, 32, 5, 6, 2, 24, 12, 8, 5, 16, 9, 16 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 A. Karttunen, Scheme-program for computing this sequence. FORMULA a(n) = A091222(A000051(n)). a(n) = Sum_{d|n} A318622(d). - Robert Israel, Aug 30 2018 MAPLE h:= proc(n) option remember;  numtheory:-phi(n)/numtheory:-order(2, n/2^padic:-ordp(n, 2)) end proc: f:= n -> add(h(d), d=numtheory:-divisors(n)): map(f, [\$1..100]); # Robert Israel, Aug 30 2018 CROSSREFS Cf. A000374 gives the number of distinct irreducible factors of the same polynomials. Sequence in context: A330631 A214560 A152858 * A082991 A214212 A100008 Adjacent sequences:  A091245 A091246 A091247 * A091249 A091250 A091251 KEYWORD nonn AUTHOR Antti Karttunen, Jan 03 2004 STATUS approved

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Last modified August 9 02:14 EDT 2020. Contains 336310 sequences. (Running on oeis4.)