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 A056679 Primes p such that 1 + x + Sum_{q prime <= p} x^q is irreducible over GF(2). 0
 2, 5, 17, 59, 73, 269 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE a(3) = 17 because 1 + x + x^2 + x^3 + x^5 + x^7 + x^11 + x^13 + x^17 is irreducible over GF(2). MATHEMATICA Do[ If[ ToString[ Factor[ 1 + x + Sum[ x^Prime[k], {k, 1, n} ], Modulus -> 2]] == ToString[ 1 + x + Sum[ x^Prime[k], {k, 1, n} ] ], Print[ Prime[ n ] ] ], {n, 1, 250}] CROSSREFS Sequence in context: A134128 A119254 A278394 * A084528 A149993 A148413 Adjacent sequences:  A056676 A056677 A056678 * A056680 A056681 A056682 KEYWORD nonn AUTHOR Robert G. Wilson v, Nov 10 2000 STATUS approved

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Last modified December 16 09:06 EST 2019. Contains 330020 sequences. (Running on oeis4.)