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A087091 Numbers k such that p = k^2 + k + 41 and p - 2 are twin primes. 2
1, 4, 10, 16, 19, 31, 34, 43, 55, 58, 61, 70, 73, 79, 85, 94, 100, 118, 148, 154, 160, 175, 196, 199, 211, 214, 223, 226, 229, 238, 253, 274, 313, 340, 424, 430, 469, 499, 508, 529, 538, 541, 550, 565, 640, 658, 673, 706, 724, 760, 763, 781 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

EXAMPLE

4 is in the sequence because 61 = 4^2 + 4 + 41 and 59 are twin primes.

MATHEMATICA

Select[Range[10^3], And @@ PrimeQ[#^2 + # + {39, 41}] &] (* Amiram Eldar, Dec 27 2019 *)

PROG

(PARI) isok(n) = isprime(n^2+n+41) && isprime(n^2+n+39); \\ Michel Marcus, Oct 03 2013

CROSSREFS

Cf. A007634, A087090.

Sequence in context: A310486 A310487 A310488 * A310489 A310490 A310491

Adjacent sequences:  A087088 A087089 A087090 * A087092 A087093 A087094

KEYWORD

nonn

AUTHOR

Zak Seidov, Aug 08 2003

STATUS

approved

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Last modified September 28 06:57 EDT 2021. Contains 347703 sequences. (Running on oeis4.)