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A136240 Numbers n among A006093 such that n^2 + n + 1 is prime. 2
1, 2, 6, 12, 66, 78, 138, 150, 162, 192, 336, 348, 378, 456, 540, 612, 642, 726, 768, 918, 990, 1020, 1092, 1116, 1200, 1230, 1380, 1422, 1548, 1566, 1596, 1620, 1692, 1746, 1788, 1800, 1932, 1986, 2010, 2016, 2112, 2136, 2142, 2238, 2280, 2556, 2646 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
See A074268 for the primes associated with a(n).
LINKS
FORMULA
a(n) = A065508(n) - 1.
MATHEMATICA
Select[Prime[Range[400]]-1, PrimeQ[#^2+#+1]&] (* Harvey P. Dale, Feb 11 2022 *)
PROG
(PARI) isA136240(n) = {isprime(n+1) && isprime(n^2+n+1)} \\ Michel Marcus, Jul 28 2013
CROSSREFS
Cf. A136241.
Sequence in context: A069047 A095921 A106037 * A090747 A287142 A076220
KEYWORD
nonn
AUTHOR
Lekraj Beedassy, Dec 23 2007
STATUS
approved

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Last modified March 28 14:38 EDT 2024. Contains 371254 sequences. (Running on oeis4.)