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A107312 Primes p such that p + 2 and p^2 + 2^2 are primes. 1
3, 5, 17, 137, 347, 827, 2087, 2687, 3557, 3917, 4517, 4967, 5477, 5657, 5867, 6827, 7457, 7547, 7877, 8087, 8537, 8597, 10037, 10427, 10937, 12107, 12377, 13397, 13877, 16067, 17837, 17987, 19427, 19697, 20507, 20717, 20807, 22367, 22637 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes are lesser twins. Except a(1) and a(2), all a(n) == 7(mod 10).

LINKS

Edward Jiang, Table of n, a(n) for n = 1..1000

MAPLE

select(p -> isprime(p) and isprime(p+2) and isprime(p^2+4), [seq(2*i+1, i=1..10000)]); # Robert Israel, Aug 11 2014

MATHEMATICA

Select[Prime[Range[3000]], PrimeQ[ #+2]&&PrimeQ[ #^2+4]&]

PROG

(MAGMA) [p: p in PrimesUpTo(25000)|  IsPrime(p+2) and IsPrime(p^2+4)] // Vincenzo Librandi, Jan 29 2011

(PARI) a(n)=isprime(n) && isprime(n+2) && isprime(n^2+4) \\ Edward Jiang, Aug O8 2014

CROSSREFS

Cf. A045637.

Sequence in context: A191222 A084723 A288376 * A083213 A171271 A056826

Adjacent sequences:  A107309 A107310 A107311 * A107313 A107314 A107315

KEYWORD

nonn

AUTHOR

Zak Seidov, May 21 2005

STATUS

approved

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Last modified April 25 04:08 EDT 2019. Contains 322450 sequences. (Running on oeis4.)