OFFSET
1,1
COMMENTS
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..10000
EXAMPLE
25, in binary '11001', encodes polynomial x^4 + x^3 + 1, which is irreducible in polynomial ring GF(2)[X], but is composite in N, thus it is a term of this sequence.
43, in binary '101011', encodes polynomial x^5 + x^3 + x + 1, which factors as (x + 1)(x^4 + x^3 + 1), i.e., 43 = A048720(3,25), and the latter factor of these, encoded by 25, is a composite in N, thus 43 is a term of this sequence.
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 02 2014
STATUS
approved