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A143428 a(n)=least prime == -1 mod 6 such that q(n)*(q(n)+a(n))-1 and q(n)*(q(n)+a(n))+1 are twin primes with q(i)=i-th prime == 1 mod 6. 4
53, 11, 11, 11, 17, 53, 197, 227, 11, 53, 17, 53, 23, 17, 179, 269, 47, 311, 17, 11, 59, 41, 11, 53, 137, 11, 83, 53, 59, 17, 47, 17, 11, 47, 173, 269, 23, 101, 11, 137, 443, 53, 107, 263, 11, 23, 251, 17, 137, 383, 479, 353, 107, 173, 71, 197, 17, 107, 101, 179, 89, 17 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Pierre CAMI, Table of n, a(n) for n = 1..10000

EXAMPLE

q(1)=7, 7*(7+5)-1=83 prime but 85 composite

7*(7+11)-1=125 composite

7*(7+17)-1=167 prime but 169 composite

7*(7+23)-1=209 composite

7*(7+29)-1=251 prime but 253 composite

7*(7+41)-1=335 composite

7*(7+47)-1=377 composite

7*(7+53)-1=419 419 and 421 twin primes so a(1)=53

CROSSREFS

Cf. A143427, A143429, A143430.

Sequence in context: A232126 A078681 A143294 * A143385 A231426 A298061

Adjacent sequences:  A143425 A143426 A143427 * A143429 A143430 A143431

KEYWORD

nonn

AUTHOR

Pierre CAMI, Aug 14 2008

STATUS

approved

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Last modified November 27 09:19 EST 2021. Contains 349365 sequences. (Running on oeis4.)