id:A133830 - OEIS Search Results

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Least positive number k<n such that the binary trinomial 1 + 2^n + 2^k is prime, or 0 if there is no such k.

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1, 1, 1, 2, 1, 1, 0, 3, 3, 2, 1, 4, 5, 1, 1, 11, 1, 6, 5, 4, 7, 3, 9, 0, 17, 15, 1, 15, 1, 6, 0, 4, 9, 14, 13, 3, 11, 25, 0, 6, 7, 0, 17, 7, 15, 2, 0, 30, 23, 6, 21, 2, 33, 1, 0, 3, 0, 14, 5, 6, 21, 19, 0, 30, 3, 1, 5, 34, 19, 26, 17, 19, 17, 5, 33, 15, 23, 27, 33, 4, 3, 26, 1, 39, 35, 19, 9, 18 (list; graph; listen)

	OFFSET	`2,4`
	COMMENT	`Sequence A081504 gives the n such that a(n)=0. For those n, A133831(n) gives the k>n for which the binary trinomial is prime.`
	LINKS	`T. D. Noe, Table of n, a(n) for n=2..2000`
	MATHEMATICA	`Table[s=1+2^n; k=1; While[k<n && !PrimeQ[s+2^k], k++ ]; If[k==n, 0, k], {n, 100}]`
	CROSSREFS	`Cf. A057732, A059242, A057196, A057200, A081091, A095056 (various forms of prime binary trinomials).` `Sequence in context: A119513 A085815 A088234 this_sequence A111571 A051509 A124816` `Adjacent sequences: A133827 A133828 A133829 this_sequence A133831 A133832 A133833`
	KEYWORD	`nonn`
	AUTHOR	`T. D. Noe (noe(AT)sspectra.com), Sep 26 2007`

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Last modified December 4 21:35 EST 2008. Contains 151309 sequences.

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