id:A098016 - OEIS Search Results

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Indices x such that (1/4)(prime(x+1) + prime(x)) is prime.

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2, 3, 9, 11, 23, 32, 54, 58, 67, 76, 86, 103, 164, 188, 200, 202, 208, 210, 243, 311, 351, 354, 374, 414, 420, 427, 441, 468, 515, 539, 559, 588, 621, 639, 650, 652, 662, 670, 693, 708, 748, 752, 769, 811, 816, 823, 842, 883, 889, 939, 943, 963, 970, 1006, 1009 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`Conjecture: 1/2(prime(x+1) + prime(x)) is not prime for all x.`
	EXAMPLE	`Prime(2+1) + prime(2) = 5+3 = 8. 1/4(8) = 2. 2 is the first entry.`
	PROGRAM	`(PARI) f(n) = for(x=1, n, y=prime(x+1)+prime(x); if(y%4==0 && isprime(y\4), print1(x", ")))`
	CROSSREFS	`Sequence in context: A057569 A049618 A057292 this_sequence A089645 A088086 A088084` `Adjacent sequences: A098013 A098014 A098015 this_sequence A098017 A098018 A098019`
	KEYWORD	`easy,nonn`
	AUTHOR	`Cino Hilliard (hillcino368(AT)gmail.com), Sep 09 2004`

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Last modified November 30 13:13 EST 2009. Contains 167758 sequences.

AT&T Labs Research