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A117243 Chen numbers which are also twin primes. 0
3, 5, 7, 11, 13, 17, 19, 29, 31, 41, 59, 71, 101, 107, 109, 137, 139, 149, 179, 181, 191, 197, 199, 227, 239, 269, 281, 311, 347, 419, 431, 461, 521, 569, 571, 599, 617, 641, 659, 809, 811, 821, 827, 829, 857, 881, 1019, 1031, 1049, 1061, 1091, 1151, 1229 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..53.

EXAMPLE

(3, 5) are twin numbers and also Chen numbers.

MAPLE

ischenprime:=proc(n); if (isprime(n) = 'true') then if (isprime(n+2) = 'true' or numtheory[bigomega](n+2) = 2) then RETURN('true') else RETURN('false') fi fi end:

ts_chen_twin_primes:=proc(n) local i, ans; ans:=[ ]: for i from 1 to n do if (ischenprime(i) = 'true') and (isprime(i+2) = 'true' or isprime(i-2) = 'true') then ans:=[op(ans), i]: fi od; RETURN(ans) end:

ts_chen_twin_primes(1230);

CROSSREFS

Cf. A001097, A109611.

Sequence in context: A132143 A239879 A001097 * A179679 A059362 A212376

Adjacent sequences:  A117240 A117241 A117242 * A117244 A117245 A117246

KEYWORD

nonn

AUTHOR

Jani Melik, Apr 22 2006

EXTENSIONS

Corrected and extended by Jani Melik, May 04 2013

STATUS

approved

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Last modified November 21 12:28 EST 2019. Contains 329370 sequences. (Running on oeis4.)