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 A091242 Reducible polynomials over GF(2), coded in binary. 48
 4, 5, 6, 8, 9, 10, 12, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 43, 44, 45, 46, 48, 49, 50, 51, 52, 53, 54, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 71, 72, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 88 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS "Coded in binary" means that a polynomial a(n)*X^n+...+a(0)*X^0 over GF(2) is represented by the binary number a(n)*2^n+...+a(0)*2^0 in Z (where a(k)=0 or 1). - M. F. Hasler, Aug 18 2014 The reducible polynomials in GF(2)[X] are the analog to the composite numbers A002808 in the integers. LINKS Robert Israel, Table of n, a(n) for n = 1..10000 A. Karttunen, Scheme-program for computing this sequence. EXAMPLE For example, 5 = 101 in binary encodes the polynomial x^2+1 which is factored as (x+1)^2 in the polynomial ring GF(2)[X]. MAPLE filter:= proc(n) local L;   L:= convert(n, base, 2);   not Irreduc(add(L[i]*x^(i-1), i=1..nops(L))) mod 2 end proc: select(filter, [\$2..200]); # Robert Israel, Aug 30 2018 CROSSREFS Inverse: A091246. Almost complement of A014580. Union of A091209 & A091212. First differences: A091243. Characteristic function: A091247. In binary format: A091254. Sequence in context: A284902 A023851 A285279 * A089253 A047432 A095279 Adjacent sequences:  A091239 A091240 A091241 * A091243 A091244 A091245 KEYWORD nonn AUTHOR Antti Karttunen, Jan 03 2004 EXTENSIONS Edited by M. F. Hasler, Aug 18 2014 STATUS approved

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Last modified September 15 16:44 EDT 2019. Contains 327078 sequences. (Running on oeis4.)