A130676 - OEIS

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A130676

Numbers n for which either 16*n^2-6*n+1 or 16*n^2-10*n-1 or both is/are prime.

1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 15, 16, 17, 18, 20, 22, 23, 25, 27, 28, 30, 32, 33, 35, 36, 37, 38, 39, 42, 43, 44, 46, 48, 50, 52, 57, 59, 60, 63, 65, 67, 68, 70, 71, 72, 73, 76, 80, 81, 85, 87, 88, 90, 92, 93, 94, 95, 98, 101, 102, 103, 104, 105, 108, 110, 112, 113, 115, 118, 120, 123, 125, 128, 129, 132, 134

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OFFSET

1,2

COMMENTS

Consider the two forms (4*n-2)*4*n +- (2*n+1), where "+-" generates two different terms 16*n^2-6*n+1 and 16*n^2-10*n-1 for n=1,2,3,...

If at least one of the two numbers is prime, n is inserted into the sequence.

LINKS

Table of n, a(n) for n=1..76.

EXAMPLE

For n=20, 16*20^2 - 10*20 - 1= (4*20-2)*4*20-(2*20+1) = 6199 is prime, which adds 20 to the sequence.

For n=15, 16*15^2 - 6*15 +1= (4*15-2)*4*15 +(2*15+1) = 3511 is prime, which adds 15 to the sequence.

CROSSREFS

Sequence in context: A011871 A377357 A229769 * A039227 A257727 A039273

Adjacent sequences: A130673 A130674 A130675 * A130677 A130678 A130679

KEYWORD

easy,nonn,less

AUTHOR

J. M. Bergot, Jun 28 2007

EXTENSIONS

Edited and extended. - R. J. Mathar, Jul 10 2011

STATUS

approved