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A086505 a(n) is the n-th smallest prime p such that p+2n is also prime. 4
3, 7, 11, 23, 31, 29, 53, 73, 53, 89, 157, 73, 137, 199, 73, 281, 229, 127, 383, 229, 149, 389, 463, 193, 359, 547, 239, 467, 823, 197, 857, 883, 283, 809, 499, 389, 1013, 907, 421, 827, 1201, 373, 1151, 1231, 367, 1307, 1279, 577, 1229, 1009, 631, 1427, 1783 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Note the patterns in the graph. These patterns depend on the number of prime factors of n: see color graph for different n's: n primes - black dots, n multiples of 3 - red dots, n multiples of 15 - green dots, n multiples of 105 - blue dots. - Zak Seidov, Nov 28 2013

LINKS

Zak Seidov, Table of n, a(n) for n = 1..10000

Zak Seidov, Color graph for different n's

MAPLE

N:= 10^4: # to get all terms before the first with a(n)+2*n > N

Primes:= select(isprime, {seq(2*i+1, i=1..N)}):

for n from 1 do

R:= Primes intersect map(`+`, Primes, -2*n);

if nops(R) < n then break fi;

A[n]:= R[n];

od:

seq(A[j], j=1..n-1); # Robert Israel, Aug 07 2014

CROSSREFS

Cf. A020483, A231608.

Sequence in context: A111668 A112038 A097452 * A239227 A154427 A287459

Adjacent sequences:  A086502 A086503 A086504 * A086506 A086507 A086508

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Jul 29 2003

EXTENSIONS

Edited by Sam Alexander, Feb 26 2004

STATUS

approved

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Last modified May 28 04:00 EDT 2020. Contains 334671 sequences. (Running on oeis4.)